Module 6: Creating and Manipulating Sets

Group Activity: Using Set Creation Functions In this group activity, you may follow along on your own computer with your instructor or observe the demonstration You will learn how to gen

Contents

Overview 1

Using Set Creation Functions 2

Lab A: Using Set Creation Functions 13

Using Set Manipulation Functions 20

Lab B: Using Set Manipulation Functions 30

Using Subquery Set Functions 36

Lab C: Using Subquery Set Functions 52

Working with Dimension Interactions 57

Lab D: Working with Dimension

Interactions 64

Review 67

Module 6: Creating and Manipulating Sets

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Instructor Notes

The ability to work with sets is critical both to retrieving data from an online analytical processing (OLAP) cube in a multidimensional expression (MDX) query statement and creating powerful MDX expressions

In this module, students will be introduced to functions that return sets of members Some of the functions retrieve sets from the metadata defined in the cube's dimensions Some of the functions manipulate those sets to create new sets that meet specific analytical purposes

After completing this module, students will be able to:

! Use functions to create a set

! Use functions to manipulate a set

! Create a set from subqueries

! Manipulate dimension interactions by using advanced functions

Materials and Preparation

This section provides you with the required materials and preparation tasks that are needed to teach this module

Required Materials

To teach this module, you need the following materials:

! Microsoft® PowerPoint® file 2093A_6.ppt

Preparation Tasks

To prepare for this module, you should:

! Read all of the materials for this module

! Read the instructor notes and margin notes

! Practice the lecture and demonstrations

! Complete the labs

! Review the Teacher Preparation materials on the Teacher Preparation compact disc

Presentation:

95 Minutes

Labs:

75 Minutes

Instructor Setup for Group Activities and Labs

This section provides setup instructions that are required to prepare the instructor computer or classroom configuration for group activities and labs All group activities and labs use the same database setup, which requires restoring a database archive

! To prepare for group activities and labs

In this procedure, you restore the Market database, which is a cab file type

1 Open Analysis Manager

2 In the left pane, expand the Microsoft Analysis Services folder

3 Expand the Server icon and verify that the Market database does not exist

4 Right-click the Server icon, and then click Restore Database

5 Navigate to the C:\Moc\2093A\Batches folder

6 Select Market.cab, click Open, and then click Restore

If the Market database already exists from a previous group exercise or lab,

and cubes within the database contain extraneous information, you can return

the Market database and its cubes to a beginning position by either:

Deleting any calculated members that were created in a specific cube, and then saving the cube

- or - Repeating the preceding restore database procedure

Other Activities

Difficult Questions

Below are difficult questions that students may ask you during the delivery of this module and answers to the questions These materials delve into subjects that are within the scope of the module but are not specifically addressed in the content of the student notes

1 Do the Members, Children, and Descendants function really create sets? These functions begin with something that is not a set—a dimension, a level, or a member—and return something that is a set In that sense, they create sets This is different from most other set functions, which begin with one or more sets and return a different set

2 How would you get all the leaf-level members of an entire dimension?

Use the Descendants function with the All Level member as the common ancestor

do, but there are exceptions As you learn a new function, you must remember its syntactic form

4 The optional flags for the Descendants function can be confusing Is there

an easy way to learn them?

In the first place, you can usually avoid using the flags of the Descendants function if you are willing to use combinations of other functions—particularly Union, Except, and Hierarchize If you do want

to use the Descendants flags, replace “before” with “above,” and

“after” with “below,” and read the arguments in the order 1, 3, 2 For

example, read the expression Descendants([1998],[Calendar

Quarter],BEFORE_AND_AFTER) as “the descendants of 1998 above

and below the calendar quarter level.”

5 The function definitions in the Syntax Examples list of the MDX2093A

application do not always match those in the Functions list of the Calculated Member Builder Which are correct?

The MDX2093A application is simply a learning tool It has many imperfections Always use the Calculated Member Builder or Books Online to find and learn unfamiliar functions

6 In both Books Online and the Functions list of the Calculated Member

Builder, the syntax for the Descendants – Level function shows that you

cannot use the third argument—Desc_flags—without also using the second argument—Level Is that true?

No You can omit the Level argument, leaving commas to show its place, and still use a flag such as LEAVES as the third argument The documentation is incorrect

to just combine the sets with braces If you want to strip duplicate members, you may want to use the Union function

8 Would you ever use the NON EMPTY keyword to create a calculated

member?

No It is used only to create a query statement that returns a report In

a calculated member, you can use the NonEmptyCrossjoin function to combine sets from multiple dimensions and remove tuples that produce

an empty result

Module Strategy

Major sections of this module begin with or include a group activity followed

by review lecture and then labs The following are guidelines for delivering materials in the context of group activities:

! Using group activities to introduce new content You often introduce new concepts or functionality while delivering the procedures in a group activity as a live demonstration For example, you may present a new MDX function by showing first its construction and then its result set as an actual calculated member formula or within a query statement

Use the topic slides that follow the group activity as a review of the content—for example, the syntax of a specific function

! Interaction with students

A group activity flows best when you deliver it as a shared exploration Ask students such questions as: “What would happen if we…?” “Why did this happen?” “Was that what you expected?” Encourage students to ask you questions about the functions being tested

! Students follow along

In some cases, you may want to encourage students to follow your live demonstration on their own computers This practice works best for simpler group activities or for a group activity that is not replicated by a later lab

It is not a problem if a student does not follow your demonstration, or if a student starts following and then stops before the group activity is completed There is no file or structure dependency between group activities

or between a group activity and a later lab

! Lab replication of group activity The exercises in the labs closely follow the group activity procedures but do not define each step or show the code answer Encourage students to write and test the MDX expressions on their own, referring back to the group activity procedures for clarification Students may also refer to answer files, which are available for each procedure in exercises

Labs are generally more challenging when students have not followed the instructor on their own computers during the group activity However, many students benefit from the two hands-on experiences of following the group activity and then completing the labs

! Answer files for group activities Where applicable, answer files are provided for each procedure in group activities If necessary to facilitate your demonstration, copy and paste the correct expression from the answer file into the Calculated Member Builder

Use the following additional strategies to present this module:

! Using Set Creation Functions Begin by explaining why it is important to be able to create a set of

members Next, describe the use of the Members function, explaining the syntax carefully Then introduce the Descendants function, describing how

it can be used to retrieve members from either a single level or from multiple levels Emphasize the fact that these functions are returning metadata about the cube, not data from the cube

! Using Set Manipulation Functions Explain why it is useful to be able to manipulate sets to create a new set that

contains specific members Introduce the Head, Tail, Union, Intersect, Except, and Hierarchize functions, describing the syntax for each and

giving examples of when to use each function

! Using Subquery Set Functions

Define the term subquery and describe when a subquery is used Emphasize

the difference between functions that look only at cube metadata and functions that use a subquery to retrieve actual data form the cube, although the function returns only a set of members and no actual data Introduce the

Order, TopCount, and Filter functions, describing the syntax for each and

explaining when to use each function

! Working with Dimension Interactions Explain that this section introduces more advanced processes that retrieve sets that combine members from two or more dimensions Then introduce

the Crossjoin function and the NON EMPTY keyword Describe the

syntax for each and explain when to use each

Overview

! Using Set Creation Functions

! Using Set Manipulation Functions

! Using Subquery Set Functions

! Working with Dimension Interactions

The ability to work with sets is critical both to retrieving data from an online analytical processing (OLAP) cube in a multidimensional expression (MDX) query statement and creating powerful MDX expressions

In this module, you will be introduced to functions that return sets of members Some of the functions retrieve sets from the metadata defined in the cube's dimensions Some of the functions manipulate those sets to create new sets that meet specific analytical purposes

After completing this module, you will be able to:

! Use functions to create a set

! Use functions to manipulate a set

! Create a set from subqueries

! Manipulate dimension interactions by using advanced functions

In this module, you will learn

about the creation and

manipulation of sets

# Using Set Creation Functions

! Group Activity: Using Set Creation Functions

! Members Function

! Children Function

! Single-Level Descendants Function

! Leaf-Level Descendants Function

In this section, you will learn the most useful functions for retrieving a set of members from the metadata of a cube These functions, when used alone, retrieve only sets of members from the cube metadata, not actual data from the cube These sets can appear as labels on the axes of a report, controlling which cube values appear

In later sections, you will learn how to manipulate these simple sets of members

The group activity introduces the use of two basic functions that generate sets—

the Members function and the Descendants function The following topics

follow the group activity:

! Members Function

This topic describes how to return members of specified levels and

dimensions by using the Members function

! Children Function This topic describes the Children function This function returns the

children of a specified member

! Single-Level Descendants Function This topic describes the Descendants function The simplest form of this

function returns a set of members at a specific level, lower in the hierarchy tree than the member and level names given in the query You can also use

the Descendants function to return all the members that descend from a

single member

! Leaf-Level Descendants Function

Topic Objective

To introduce functions that

retrieve a set of members

from the metadata of a

cube

Lead-in

In this section, you will learn

the most useful functions for

retrieving a set of members

from the metadata of a

cube

Delivery Tip

Briefly explain the bullets on

this diamond slide to provide

context for the upcoming

group activity in which the

items are functionally

demonstrated

Group Activity: Using Set Creation Functions

In this group activity, you may follow along on your own computer with your instructor or observe the demonstration

You will learn how to generate sets by using the Members and Descendants

functions Once you understand these functions, you can easily learn other related functions

! To open the MDX2093A application and template file

In this procedure, you use the MDX2093A sample application to open templates you will use in the remainder of the group activity

1 In Microsoft® Windows® Explorer, navigate to C:\MOC\2093A\LabFiles,

double-click MDX2093A.exe, and then click OK to connect to the server

2 When asked to open a query file, navigate to the folder

C:\MOC\2093A\LabFiles\L06, and open the file SetCreate.mdx

3 In the DB list, select Market, and then in the Cube list, select Sales The

first template looks like the following text:

Members of a Dimension - SELECT

{[Sales Dollars], [Sales Units]} ON COLUMNS, «Set» ON ROWS

FROM Sales

Topic Objective

To learn how to create sets

by using the Members and

Descendants functions

Lead-in

In this group activity, you will

learn how to generate sets

of members

Delivery Tip

Explain initial template

before continuing with the

group activity

! To show all the members of a dimension

In this procedure, you use the Members function to create a set that

consists of all members of all levels of a dimension

1 Click in the «Set» token of the Members of a Dimension query In the Syntax Examples list, expand the Set folder, and then double-click Members – Dimension

MDX includes three different Member functions: one each for Level, Dimension, and Hierarchy The Dimension and Hierarchy versions are

essentially identical: simply think of the dimension and hierarchy together

as the name of the dimension

2 Click in the «Dimension» token, and then in the Data list, double-click the Product dimension The resulting statement looks like this:

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, [Product].Members ON ROWS

FROM Sales

3 To view the results of the query, click the Run Query button

The labels on the Rows axis appear from all levels of the Product hierarchy The member names in a level are sorted according to the Order

By Column property defined in the dimension

The MDX2093A application displays members from multiple levels in a single column, but indented This differs from the browser in the Analysis Manager and the Microsoft Office PivotTable® list, which use a separate column for each level It is the client application—not the MDX statement—that determines how levels are displayed

! To show the children of a member

In this procedure, you use the Children function to create a set that consists of

members that are the children of a specified member

1 In the Queries list, select Children of a Member

2 Click in the «Set» token In the Syntax Examples list, expand the Set folder, and then double-click Children

The Children function must follow a single member Do not confuse the Children function with the Members function A member has children A

level or a dimension has members

3 Click in the «Member» token and then type [Bagels] The resulting

statement looks like this:

SELECT {[Sales Dollars],[Sales Units]} ON COLUMNS, Bagels.Children ON ROWS

FROM Sales

4 To view the results of the query, click the Run Query button

The Rows axis contains the five members that have Bagels as a parent The Children function is analogous to the Parent function The Parent function goes up the tree, whereas the Children function goes down the tree The Parent function returns a member, whereas the Children function returns

a set That is because a member can have more than one child, but a member never has more than one parent

! To show single-level descendants of a member

In this procedure, you use the Descendants function to create a set of members

that are all descendants of one specified member

1 In the Queries list, select Descendants at a Level

2 Click in the «Set» token In the Syntax Examples list, expand the Set folder, and then double-click Descendants

3 Remove brackets around optional arguments, and then delete the third argument

The first argument is a member It is the common ancestor for all the members returned by the function

4 Click in the «Member» token and type [Bread]

The second argument is a level It is the level from which you want to retrieve members

5 Click in the «Level» token and type [Product Name] The resulting

statement looks like this:

SELECT {[Sales Dollars],[Sales Units]} ON COLUMNS, Descendants([Bread],[Product Name]) ON ROWS FROM Sales

6 To view the results of the query, click the Run Query button

The set of members on the Rows axis comes from the Product Name level but includes only those products that share Bread as a common ancestor The Descendants function is analogous to the Ancestor function—that

is, in both cases you can specify a starting member and a level As with the

Ancestor function, you can specify the level for the Descendants function by

using either an explicit level name or a relative numeric value that gives the distance or number of levels to skip

! To show all the descendants of a member

In this procedure, you use the Descendants function to create a set of all the

members that are descendants of a specified member

1 In the Queries list, select All Descendants

2 Click in the «Set» token In the Syntax Examples list, expand the Set folder, and then double-click Descendants

3 Delete everything except the first argument

If you include only the common ancestor member in the Descendants

function, it returns all the descendants of that member at all remaining levels

of the hierarchy

4 Click in the «Member» token and type [Bread] The resulting statement

looks like this:

SELECT {[Sales Dollars],[Sales Units]} ON COLUMNS, Descendants([Bread]) ON ROWS

! To create a set of the leaf-level descendants of a member

In this procedure, you use the Descendants function to create a set of the

level members of a parent-child dimension In a parent-child dimension, level members—members that have no children—are not always on the same level

leaf-1 In the Queries list, select Leaf-Level Descendants

2 Click in the «Set» token In the Syntax Examples list, expand the Set folder, double-click Descendants, and then delete any brackets indicating

5 Click in the «Desc_flags» token, and then type LEAVES The resulting

statement looks like this:

SELECT {[Sales Dollars],[Sales Units]} ON COLUMNS, Descendants(Employee, , LEAVES) ON ROWS FROM Sales

6 To view the results of the query, click the Run Query button

The set of members on the Rows axis consists of all the leaf-level members

of the Employee dimension, although those members occur on different

levels None of the summarized members appears in the set

Members Function

! Returns a Specified Set of Members

! Retrieves All Members of a Level or Dimension

! Must Use Hierarchy Version If the Dimension Has Explicit Hierarchy

! The Members function works not only with the members of a level, but can

also be used to retrieve all the members of a dimension

When you have a large dimension, retrieving all the members of the dimension can create a very large set Use caution when you use the

Members function with a dimension

! In the Set group of the Functions list, the Members – Hierarchy function

appears This means that if a dimension has a hierarchy—for example, the

Topic Objective

To explain the syntax and

results of the Members

function

Lead-in

The Members function

returns members of specific

Because students have

already been exposed to the

Members function in the

previous group activity, treat

this topic as a review—that

is, do not spend a lot of

time

Caution

MDX includes the following other functions that return sets similar to the

Members function:

! The AllMembers function returns all the members of a level or dimension,

including any calculated members

! The AddCalculatedMembers function adds any calculated members to a

These related functions are

included for reference only

Do not spend any time

explaining them

Children Function

! Returns a Set of Children of a Member

! Is Similar to the Parent Function

$ Moves down the tree instead of up

$ Returns a set instead of a single member

! Is Easy to Confuse with Members Function

! Appears in the Set Group of the Syntax Examples List

[1998].Children

Returns the set of all quarters in 1998

The Children function returns members that have the specified member as a

• The Children function moves down the tree, whereas the Parent

function moves up

• The Children function returns a set, whereas the Parent function

returns a single member

! The Children function is easy to confuse with the Members function

because both return a set of members Following are the important differences:

• A level (or dimension) has Members

• A member has Children

! Because the Children function returns a set, it appears in the Set group of the Syntax Example list

MDX includes the following other function that returns sets similar to the

Children function:

Topic Objective

To explain the syntax and

results of the Children

function

Lead-in

The Children function

returns members that share

a common parent

Example

Delivery Tip

Because students have

already been exposed to the

Children function in the

previous group activity, treat

this topic as a review—that

is, do not spend a lot of

time

Ask why Children returns a

set whereas Parent returns

a member Because the

hierarchy, by definition, gets

larger as you move down

Related Functions

Single-Level Descendants Function

! Returns a Set of Members at a Specific Level or Distance

! Is Similar to the Ancestor Function, but Moves Down

! Returns Descendants at All Levels If You Omit Level

! Appears in the Set Group of the Syntax Example List

The Ancestor function returns a single member at a specific level, higher in the

hierarchy tree The Descendants function, in turn, returns a set of members

Descendants(«Member»,[«Level»])

The following example returns the set of all months in 1998

Descendants([1998], [Calendar Month])

The following example returns all the descendants of Bread, at all levels of the

hierarchy

Descendants([Bread])

When you use the Descendants function, consider the following facts and

guidelines:

! The most common form of the Descendants function returns the members

of a level that are descendants of a specified member In place of a level, you can give a numeric value that specifies the distance—that is, the number

of levels between the specified member and the resulting members

! The Descendants function is analogous to the Ancestor function: you give

it a starting member and a level name or distance number The only

difference is that the Ancestor function moves up, and the Descendants

function moves down

! If you omit the level argument from the Descendants function, it returns all

the members that descend from the specified member, without regard to the level In effect, you get the subtree with the specified member as the top member

! Because the Descendants function returns a set of members, it appears in the Set group of the Syntax Example list

Topic Objective

To describe how the

Descendants function can

be used to return a set of

members at one level

Lead-in

The Descendants function

is similar to the Ancestor

Because students have

already been exposed to the

Descendants function in

the previous group activity,

treat this topic as a review—

that is, do not spend a lot of

time

Ask why Descendants

returns a set whereas

Ancestor returns a

member Because the

hierarchy, by definition, gets

larger as you move down

Leaf-Level Descendants Function

! Optional Third Argument Adds Flags

! LEAVES Flag Returns Only Descendants at Leaf-Level

Descendants([Maya Gutierrez], , LEAVES))

Returns leaf-level descendants of Maya at any level

Returns leaf-level descendants of Maya at any level

The Descendants function can also return a set that consists only of leaf-level

members This is particularly useful with a parent-child dimension, where the leaf-level members may occur on different levels

To return a set that includes only leaf-level members, you use an optional third argument to specify the levels from which you want to return the descendants

Descendants(«Member», [«Level»],LEAVES)

The following example returns all the employees who report—directly or indirectly—to Maya Gutierrez

Descendants ([Maya Gutierrez], , LEAVES))

MDX includes the following other functions that return sets similar to the

Descendants function:

! The Descendants function has additional optional arguments that allow you

to return various subsets of the descendants of a member

! The Ancestors function returns the set of ancestors between a specified

member and a specified level—or the top of the tree—with one member from each level

You can find more information about these functions by searching on the function name in Microsoft SQL Server Books Online

Topic Objective

To describe how the

Descendants function can

be used to return the

leaf-level members under a

specified member

Lead-in

The Descendants function

can also be used to return a

set of members that are all

Because students have

already been exposed to the

Descendants function in

the previous group activity,

treat this topic as a review—

that is, do not spend a lot of

time

Delivery Tip

These related functions are

included for reference only

Do not spend any time

explaining them

Lab A: Using Set Creation Functions

Objectives

After completing this lab, you will be able to:

! Create sets by using the Members and Descendants functions

Prerequisites

Before working on this lab, you must have successfully completed modules 1

through 5 in course 2093A, Implementing Business Logic with MDX in

In this lab, you will create

sets by using the Members

and Descendants

functions

Explain the lab objectives

Exercise 1

Using Set Creation Functions

In this exercise, you will use functions that retrieve a set from a dimension—the

Members function and the Descendants function

As you complete each procedure, compare the result as shown in the procedure screen shot to the result on your own computer If there is a difference, recheck your entry and refer back to the related group activity procedures as necessary

If you still cannot reconcile your result, then refer to the answer file, which is located in:

! The Market database

! The Sales cube

If these objects do not exist in Analysis Manager, you must perform the following procedure before you continue with this lab

! To restore the Market database

1 In the left pane of Analysis Manager, expand the Microsoft Analysis Services folder

2 Right-click the Server icon, and then click Restore Database

3 Navigate to the C:\Moc\2093A\Batches folder

4 Select Market.cab, click Open, and then click Restore

Delivery Tip

The procedures in this

exercise essentially

replicate the previous group

activities but without the

answers

Students having difficulty

with the procedures should

first refer back to the group

activity procedures and then

go to the answer file for

guidance

! To show all the members of a dimension

In this procedure, you use the Members function to generate a report that includes all members of the Employee dimension MembersDimension.txt in

the Answer folder is the completed MDX expression used in this procedure

1 In Windows Explorer, navigate to C:\MOC\2093A\LabFiles, double-click

MDX2093A.exe, and then click OK to connect to the server

2 When asked to open a query file, navigate to the folder

C:\MOC\2093A\LabFiles\L06, and double-click the file LabA.mdx

1 In the DB list, select Market, and then in the Cube list, select Sales

2 Modify the initial MDX statement to create a report that shows Sales Dollars and Sales Units across the Columns axis and all the members of the Employee dimension down the Rows axis

What MDX query statement did you use?

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Employee.Members ON ROWS

FROM Sales

3 Click the Run Query button , and then verify that the Results pane, which is

located in the lower left corner of the MDX Builder, appears similar to the following table

! To show the children of a member

In this procedure, you use the Children function to create a set that consists of

members that are the children of a specified member MemberChildren.txt in the Answer folder is the completed MDX expression used in this procedure

1 With the LabA.mdx file open in the MDX2093A sample application, in the

Queries list, select Children of a Member

2 Modify the initial MDX statement to create a report that shows Sales Dollars and Sales Units across the Columns axis and all the children of Meat down the Rows axis

What MDX query statement did you use?

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Meat.Children ON ROWS

FROM Sales

3 Run the query, and then verify that the Results pane appears similar to the following table

! To show single-level descendants of a member

In this procedure, you use the Descendants function to generate a report that

displays a set of members from a single level that share a common ancestor MembersDescendantsLevel.txt in the Answer folder is the completed MDX expression used in this procedure

1 With the LabA.mdx file open in the MDX2093A sample application, in the

Queries list, click Descendants on a Level

2 Modify the initial MDX statement to create a report that shows Sales Dollars and Sales Units across the Columns axis and all the Meat products

down the Rows axis

What MDX query statement did you use?

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Descendants([Meat],[Product Name]) ON ROWS FROM Sales

3 Run the query, and then verify that the first few rows of the Results pane appear similar to the following table

! To show all the descendants of a member

In this procedure, you use the Descendants function to generate a report that

displays all the descendants of a common ancestor from multiple levels

MembersDescendantsAll.txt in the Answer folder is the completed MDX expression used in this procedure

1 With the LabA.mdx file open in the MDX2093A sample application, in the

Queries list, select All Descendants

2 Modify the initial MDX statement to create a report that shows Sales Dollars and Sales Units across the Columns axis and all the descendants of USA down the Rows axis

What MDX query statement did you use?

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Descendants([USA]) ON ROWS

FROM Sales

3 Run the query, and then verify that the Results pane appears similar to the following table

! To show all the leaf-level descendants of a member

In this procedure, you use the Descendants function to generate a report that

displays all the leaf-level descendants of a common ancestor

MembersDescendantsLeaves.txt in the Answer folder is the completed MDX expression used in this procedure

1 With the LabA.mdx file open in the MDX2093A sample application, in the

Queries list, select Leaf-Level Descendants

2 Modify the initial MDX statement to create a report that shows Sales Dollars and Sales Units across the Columns axis and all the leaf level descendants of Maya Gutierrez down the Rows axis

What MDX query statement did you use?

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Descendants([Maya Gutierrez], , LEAVES) ON ROWS FROM Sales

3 Run the query, and then verify that the Results pane appears similar to the following table

# Using Set Manipulation Functions

! Group Activity: Using Set Manipulation Functions

! Head and Tail Functions

After you have returned a set of members—whether by using braces with

individual members or by using a function such as Members or Descendants—you can then modify the set

The group activity introduces several functions you can use to manipulate sets The following topics follow the group activity:

! Head and Tail Functions

This topic describes how to extract the specified number of members from

the beginning or end of the original set by using the Head and Tail

functions

! Union Function This topic describes how to combine two sets by using the Union function

The members in the sets must come from the same dimension, but they can

be from any level

! Other Set Combination Functions This topic describes how to use other functions that return a new set based

on two original sets These functions are:

• The Intersect function, which creates a set containing only those

members that are in both source sets

• The Except function, which creates a set containing only those members

that are in the first set but are not in the second set

! Hierarchize Function

This topic describes how to sort any set in the hierarchy order by using the

Hierarchize function

Topic Objective

To introduce functions that

enable modification of a set

of members

Lead-in

After you have a set of

members, you can then

modify the set to contain

only specific members

Delivery Tip

Briefly explain the bullets on

this diamond slide to provide

context for the upcoming

group activity in which the

items are functionally

demonstrated

Group Activity: Using Set Manipulation Functions

In this group activity, you may follow along on your own computer with your instructor or observe the demonstration

You will learn how to use functions that take existing sets—created by using

either set creation functions, such as Members and Descendants, or explicit

members enclosed in braces—and modify them to create new sets

! To display the first members of a set

In this procedure, you learn how to use the Head function to extract the first

members from the beginning of a set

1 In the MDX2093A application, click the Open Query File button, navigate

to the C:\MOC\2093A\Labfiles\L06 folder, and then double-click

SetManipulate.mdx

2 In the Queries list, click First Members of a Set The initial query looks

like this:

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Subcategory.Members ON ROWS

FROM Sales

If you run this query, the Rows axis displays all 12 subcategories You can

remove all but the first three by using the Head function

3 Change definition of the set on the Rows axis to Head(Subcategory.Members,3) The final query looks like this:

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Head(Subcategory.Members,3) ON ROWS

FROM Sales

Topic Objective

To learn how to manipulate

sets by using functions

Lead-in

In this group activity, you will

learn how to manipulate

existing sets to create new

4 Run the query

The Rows axis displays only the first 3 subcategories

! To display the last member of a set

In this procedure, you use the Tail function to extract the one final member

from the end of a set

1 In the Queries list, select Last Member of a Set

2 Change the definition of the set on the Rows axis to Tail(Subcategory.Members,1). The final query looks like this:

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Tail(Subcategory.Members,1) ON ROWS

FROM Sales

3 Run the query

The Rows axis displays only the last subcategory—Hot Dogs This is a

single member, but it is still a set

! To create the union of two sets

In this procedure, you use the Union function to combine two sets

1 In the Queries list, select Union of Two Sets

2 Click in the «Set» token on the Rows axis, and then in the Set folder of the Syntax Examples list, double-click the Union function

The Union function requires two sets and includes an optional third argument

3 Delete the optional third argument, along with the comma and the brackets

4 Click in the first «Set» token, and then enter [Calendar Year].Members This expression returns a set of all the members of the Calendar Year

5 Click in the second «Set» token, and then enter [Calendar Month].Members This expression returns a set of all the members of the Calendar Month level The resulting statement looks like this:

SELECT {[Sales Dollars],[Sales Units]} ON COLUMNS, Union([Calendar Year].Members, [Calendar Month].Members)

ON ROWS FROM Sales

6 To view the results of the query, click the Run Query button

The Rows axis now displays the years and also the months The values are

from different levels but appear as part of the same set The Union function

does not rearrange the members in any way; it simply returns all the members of the first set followed by all the members of the second set

If you omit the optional third argument, with the value ALL, the Union

function discards duplicate members from the result set If you do include the ALL argument, duplicate members are retained in the result

In order to combine two sets by using the Union function, the two

sets must be from the same dimension

! To arrange members of a set in hierarchy order

In this procedure, you use the Hierarchize function to sort a set into hierarchy

order

1 In the Queries list, select Hierarchize This initial query matches the final

query of the preceding procedure

2 Click before the Union function, and then in the Set group of the Syntax Examples list, double-click Hierarchize

3 Delete the «Set» token and the closing parenthesis, and then add a closing parenthesis after the closing parenthesis of the Union function The final

statement looks like this:

SELECT {[Sales Dollars],[Sales Units]} ON COLUMNS, Hierarchize(Union([Calendar Year].Members, [Calendar Month].Members)) ON ROWS

FROM Sales

Point out the order of the

members Ask the students

if this is the way that a

report should appear

4 Click the Run Query button

The Rows axis now displays the years interleaved in the proper order The

Hierarchize function simply wraps around any set, sorting the set into the

hierarchy order defined in the dimension

! To remove specific members from a set

In this procedure, you use the Except function to remove specific members

from a set This is equivalent to what you do in the PivotTable list browser when you deselect individual members from a non-measures dimension

The Except function returns a set, based on two original sets, that contains

members that are in the first set but not the second This gives the effect of removing the members of the second set from the first set

1 In the Queries list, select Remove Members from a Set

The original set expression on the Rows axis is Subcategory.Members That set displays all 12 subcategory members You can remove explicit

members—for example, Milk and Cheese—by using the Except function

2 Before the original expression, type Except(

3 After the original expression, type , {Milk, Cheese}) The final statement

looks like the following:

SELECT {[Sales Dollars], [Sales Units]} ON COLUMNS, Except(Subcategory.Members, {Milk, Cheese}) ON ROWS FROM Sales

The second argument of the Except function—the members you exclude—

must be a set Thus, if you use one or more explicit member names, they must

be enclosed in braces You can also use a set function as the second argument

For example, the expression Except([Time].[Calendar].Members,[Calendar Quarter].Members) returns a set of all the members of the Time.Calendar

dimension except the quarters

Head and Tail Functions

Returns the last four members

of the Calendar Month level

Returns the last four members

of the Calendar Month level

Returns the first four members

of the Calendar Month level

Returns the first four members

of the Calendar Month level

The Head and Tail functions return the specified number of members from the

beginning or end of the original set

These functions do not sort or rearrange the starting set in any way

Even if you extract a single member from the set, the result is still a set The

Head and Tail functions always generate sets

Head Function

The Head function returns members from the beginning of a set

Head («Set», «Number of Members»)

To return the first four members of the Months level, use the following query:Head({[Fiscal Period].[Months].Members}, 4)

Tail Function

The Tail function returns members from the end of a set

Tail («Set», «Number of Members»)

To return the last four members of the Months level, use the following query:Tail({[Fiscal Period].[Months].Members}, 4)

MDX includes the following other function that returns sets similar to the Head and Tail functions:

! The Subset function returns a specified range of members from a specified

Topic Objective

To describe Head and Tail

functions

Lead-in

The Head and Tail functions

extract a specified number

of members from either the

beginning or the end of a

set

Delivery Tip

Because students have

already been exposed to the

Head and Tail functions in

the previous group activity,

treat this topic as a review—

that is, do not spend a lot of

Union Function

! Returns a Set That Is the Combination of Two Sets

! Default Discards Duplicates; Optional ALL Retains Duplicates

! Equivalent to Enclosing Both Sets in Braces

! Appears in the Set Group of the Syntax Examples List

Union([Calendar Year].Members, [Calendar Quarter].Members)

Union([Calendar Year].Members, [Calendar Quarter].Members)

Returns years and quarters, with years preceding quarters

Returns years and quarters, with years preceding quarters

The Union function combines two sets into one The members in the sets must

come from the same dimension—but they can be from any level

Union («Set1», «Set2» [, ALL])

The following example returns Years and Quarters

Union([Calendar Year].Members,[Calendar Quarter] Members)

When you use the Union function, consider the following facts and guidelines:

! As a default, the Union function discards any members that occur more than

once in the combined set If you want to retain all members from the

original sets, use the optional All keyword

! Rather than explicitly use the Union function, you can include the sets,

separated by commas, in a pair of braces, because braces around sets simply combine the sets

When you use braces to combine the sets—whether with a plus sign or with commas—duplicate members are not discarded In order to discard

duplicate members, you must use the Union function

! Because the Union function returns a set, it appears in the Set group of the Syntax Example list

Topic Objective

To describe the Union

function

Lead-in

The Union function allows

you to combine any two sets

from the same dimension

into one set

Syntax

Example

Delivery Tip

Because students have

already been exposed to the

Union function in the

previous group activity, treat

this topic as a review—that

is, do not spend a lot of

time

Other Set Combination Functions

KY IN MI IL

NY MA CT NJ

Set2

KY IN MI IL

NY MA CT NJ

CA OR WA AZ

KY IN MI IL

NY MA CT NJ

In addition to the Union function, you can use the Intersect and Except

functions to return a new set based on two original sets In all three cases, the two original sets must contain members from the same dimension

The following are definitions of the three functions:

! The Union function creates a set containing all members from the two

source sets

! The Intersect function creates a set containing only those members that are

in both source sets

! The Except function creates a set containing only those members that are in

the first set, but are not in the second set

You can create the union of two sets—equivalent to using the Union

function—by enclosing both sets in a pair of braces separated by a plus sign

(+) You can also subtract one set from another—equivalent to the Except

function—by enclosing both sets in a pair of braces separated by a minus sign (-)

Topic Objective

To introduce the Intersect

and Except functions

Lead-in

The Intersect and Except

functions also return a

single set of members

based on two original sets

from the same dimension

Delivery Tip

Because students have

already been exposed to the

Intersect and Except

functions in the previous

group activity, treat this topic

as a review—that is, do not

spend a lot of time

Note

Hierarchize Function

! Returns Set Arranged in Hierarchy Order

! Wraps Around Existing Set Expression

! Appears in the Set Group of the Syntax Examples List

Hierarchize(Union([Calendar Year].Members, [Calendar Quarter].Members)))

Hierarchize(Union([Calendar Year].Members, [Calendar Quarter].Members)))

Returns Years and Quarters in hierarchy order

Returns Years and Quarters in hierarchy order

Combining two sets—particularly by using the Union function—often results

in a set that is not arranged in hierarchy order You can use the Hierarchize

function to sort any set in the hierarchy order

Hierarchize(«Set»)

To return Years and Quarters in the hierarchical order defined in the dimension, use the following expression

Hierarchize(Union([Calendar Year].Members, [Calendar Quarter].Members) )

When you use the Hierarchize function, consider the following facts and

guidelines:

! You use the Hierarchize function by wrapping—that is, enclosing the

function around—an existing set expression

! Because the Hierarchize function returns a set, it appears in the Set group

of the Syntax Examples list

MDX includes the following other function that adjusts a set similar to the

Hierarchize function:

! The Distinct function removes all duplicate members from a set

You can find more information about this function by searching on the function name in Microsoft SQL Server Books Online

Topic Objective

To describe the Hierarchize

function

Lead-in

The Hierarchize function

allows you to sort any set

into the hierarchy order

Syntax

Example

Delivery Tip

Because students have

already been exposed to the

Hierarchize function in the

previous group activity, treat

this topic as a review—that

is, do not spend a lot of

time

Related Functions

Delivery Tip

These related functions are

included for reference only

Do not spend any time

explaining them

Lab B: Using Set Manipulation Functions

Objectives

After completing this lab, you will be able to:

! Use functions to create new sets of members from previously existing sets

of members

Prerequisites

Before working on this lab, you must have successfully completed modules 1

through 5 in course 2093A, Implementing Business Logic with MDX in

In this lab, you will

manipulate existing sets of

members to create new sets

by using set manipulation

functions

Explain the lab objectives

Exercise 1

Using Functions to Manipulate Sets

In this exercise, you will manipulate sets to create new sets

As you complete each procedure, compare the result as shown in the procedure screen shot to the result on your own computer If there is a difference, recheck your entry and refer back to the related group activity procedures as necessary

If you still cannot reconcile your result, then refer to the answer file, which is located in:

C:\MOC\2093A\Labfiles\L02B1\Answers

You can copy and paste expressions from this file into the query pane for any given procedure

! To display the first members of a set

In this procedure, you manipulate a set to create a new set containing the first

four members from the beginning of an original set by using the Head function

ManipulateHead.txt in the Answer folder is the completed MDX expression used in this procedure

1 In Windows Explorer, navigate to C:\MOC\2093A\LabFiles, double-click

MDX2093A.exe, and then click OK to connect to the server

2 When asked to open a query file, navigate to the folder

C:\MOC\2093A\LabFiles\L06 and open the file LabB.mdx

3 In the DB list, select Market, and then in the Cube list, select Sales

4 Modify the set on the Rows axis to create a report that shows the first four

members of Product Name

What MDX query statement did you use?

SELECT {[Sales Dollars], [Sales Units]}

Head([Product Name].Members, 4) ON ROWS FROM Sales

5 Run the query, and then verify that the Results pane appears similar to the following table

Delivery Tip

The procedures in this

exercise essentially

replicate the previous group

activity but without the

answers