data warehousing architecture andimplementation phần 9 pps

To Print a R/ OLAP XL Report: Modifying a R/OLAPXL Report A R/OLAPXL report can be modified through any of the following actions: • Adding a new R/OLAPXL or Derived column • Moving or d

Opening a R/OLAPXL Report

After an appropriate data source has been selected, you may open an existing R/OLAPXL Report

To open an existing R/ OLAP XL Report:

Step 1 From the File menu, choose Open -or-

Click on the standard Open button on the MS Excel toolbar

Step 2 Use the dialog box to select the existing R/OLAPXL file -or-

Type the appropriate path and file name

Use any of the MS Excel files (* xls) provided in the Samples folder under the RolapXL

Running the R/OLAPXL Report

When the report (MS Excel file) has opened successfully, you will find the report as it was last saved

If the report had been run in the past, the retrieved data should still be visible on the worksheet

Running the report causes R/OLAPXL to retrieve the requested data from the database Any previously retrieved data are overwritten automatically with "fresh" data from the

database

To Run a R/ OLAP XL Report:

Step 1 From the R/OLAPXL menu, choose Run Report -or-

Click on the Run Report button on the R/OLAPXL toolbar

Note

Depending on its size and complexity, a R/OLAPXL report may take anywhere between a few seconds to several minutes to complete

Printing a R/OLAPXL Report

Printing a R/OLAPXL Report is no different from printing a MS Excel worksheet

To Print a R/ OLAP XL Report:

Modifying a R/OLAPXL Report

A R/OLAPXL report can be modified through any of the following actions:

• Adding a new (R/OLAPXL or Derived) column

• Moving or deleting an existing (R/OLAPXL or Derived) column

• Assigning a new constraint

• Editing an existing constraint

• Rerunning a report against new data

These topics are covered in more detail in the following sections

Creating a R/OLAPXL Report

R/OLAPXL saves data in MS Excel files MS Excel for Windows 95 saves a set of worksheets together as an MS Excel workbook The files are saved with the file name extension

* xls

Each workbook contains all retrieved data, charts, formulas, and formats that you have defined The workbook is also used to store the parameters of the R/OLAPXL reports you have created

You will find that opening and saving a R/OLAPXL report is no different from opening and saving an MS Excel workbook

When you open a new MS Excel workbook, the workbook file is a standard MS Excel file with blank sheets None of the worksheets have been initialized as R/OLAPXL worksheets Turn the active MS Excel spreadsheet into a R/OLAPXL worksheet by selecting a Schema with which to work By selecting the Schema, you select the database tables from which

you will retrieve data

Once a Schema has been selected, R/OLAPXL loads the appropriate data and transforms the

MS Excel worksheet into a R/OLAPXL worksheet

To create a new R/ OLAP XL Report:

Step 1

Open a new MS Excel workbook, or open any existing MS Excel workbook

Step 2 Select a Schema with which to work From the R/OLAPXL menu, choose Select Schema -or-

On the R/OLAPXL toolbar, click the Select Schema button

Step 3

On the pop-up window that appears, click on the desired Schema, then click on the

Select command button to confirm your selection

Warning

Do not select a new Schema while you are in the process of defining a R/OLAPXL report Doing so will make R/OLAPXL discard any changes made to the currently active sheet

Saving R/OLAPXL Reports

When you close a file, MS Excel checks to see whether you've made changes to it If you haven't made any changes, the file closes If you have made changes, MS Excel asks you whether you want to save them

To save a R/ OLAP XL Report for the first time:

Step 3 When you've typed the name of the R/OLAPXL report and selected the

desired directory, choose OK

Note that this procedure is no different from saving an MS Excel workbook for the first time

To save an existing R/ OLAP XL Report:

Step 1 From the File menu, choose Save -or- Click on the Save toolbar button

Note that this procedure is no different from saving an MS Excel workbook

Warning

Do not attempt to save a R/OLAPXL workbook in an earlier version of MS Excel This tool is not downward compatible

Closing a R/OLAPXL Report

Closing a R/OLAPXL Report is no different from closing any MS Excel workbook

To close a R/ OLAP XL Report:

Step 1 From the File menu, choose Close -or- Double-click the workbook's Close

box

If you've made changes to the workbook since you last saved it, MS Excel will ask whether you want to save your changes before closing

Step 2 Choose Yes to save your changes and close the workbook

If you don't want to save your changes, Choose No; MS Excel will close the file

without saving your changes

Working with R/OLAPXL Columns

Specify the data items to be retrieved from the data warehouse or data mart by adding R/OLAPXL Columns to your worksheet

Note

You can only include data items that are available from the Schema you had selected

earlier

A R/OLAPXL column is the most basic unit of data that appears on a R/OLAPXL report Each

column corresponds to a field from either the Fact table or the Dimension tables

You can have as many R/OLAPXL columns in your report as you wish, provided that these data elements are available from the selected schema or are derivable from fields in the selected schema

Adding a R/OLAPXL Column

Add as many R/OLAPXL Columns to the MS Excel spreadsheet as are necessary to produce the report you need

To Add a R/ OLAP XL Column to a Report:

Step 1

Position the cursor on the MS Excel column you wish to use

Step 2 From the R/OLAPXL menu, choose Assign R/OLAPXL Column -or-

On the R/OLAPXL toolbar, click on the Assign R/OLAPXL Column button

Step 3

On the pop-up window, select the appropriate Fact or Dimension Table you wish to

use

Step 4

On the same pop-up window, select the appropriate Fact or Dimensional Attribute

you wish to use

Step 5 Click on the Place command button to place the selected Fact or

Dimensional Attribute on the column -or- If your cursor is not positioned on the

appropriate column, use the Left and Right command buttons to position the cursor on the correct column before clicking on Place -or-

Click on the Insert command button to insert a column This will also place the

selected attribute on the newly inserted column

Step 6

Use the Delete command button to delete the current column if desired

Step 7

Use the Close command button to close the pop-up window when you have

finished adding columns to your report

Moving a R/OLAPXL Column

You can easily change the sequence of R/OLAPXL Columns in your report by using the R/OLAPXL toolbar

To Move a R/ OLAP XL Column:

Deleting R/OLAPXL Columns

Deleting a R/OLAPXL Column is no different from deleting any MS Excel column Several options are available, each supported by the standard MS Excel software

To Delete a R/ OLAP XL Column, Option 1:

Step 1

Select the column to delete by clicking on the column heading

Step 2

From the Edit Menu, Choose Delete

To Delete a R/ OLAP XL Column, Option 2:

Step 1

Select any cell on the column you wish to delete

Step 2

From the Edit Menu, Choose Delete

Deleting a column from a R/OLAPXL worksheet does not delete data from the data

warehouse or the data mart

Using Derived Columns

R/OLAPXL allows you to enter formulas to derive new values based on data retrieved from the data warehouse or data mart These derived columns can be inserted anywhere in the R/OLAPXL report

The cells with these formulas automatically recompute when new data are retrieved from the data warehouse or data mart

R/OLAPXL supports the following functions:

• SUM Applicable to numeric attributes, this function causes R/OLAPXL to add up the values of the factual attribute for all records that meet the constraints of the report This is the default setting for any numeric fact

• COUNT Applicable to all attributes, this function causes R/OLAPXL to count the number of records that meet the constraints of the report

• MIN Applicable to dates and numeric attributes, this function causes R/OLAPXL to return the smallest distinct value of the factual attribute for all records that meet the constraints of the report

• MAX Applicable to dates and numeric attributes, this function causes R/OLAPXL

to return the largest distinct value of the factual attribute for all records that meet the constraints of the report

• NONE Applicable only to dimensional attributes, this function causes R/OLAPXL

to return one row for each record that meets the constraints of the report This is the default setting for all dimensional attributes

Note

You can enable the DISTINCT option when using R/OLAPXL functions It instructs the database server to retrieve relevant rows and apply the used function only on unique instances of a particular record

Drilling Up and Down Using R/OLAPXL Columns

R/OLAPXL supports two types of drills: ad hoc drills and hierarchical drills

Ad Hoc Drills

Each time you add a Dimensional Attribute to your report, you are performing an ad hoc

drill For example, if your report currently has three columns—Country, Region, and Sales—you can drill further down by adding another dimensional attribute (e.g., Branch) before the Sales Fact column

In general, as the dimensional attributes in your report increase, so will the level of detail

of the facts in the report

Hierarchical Drills

A hierarchical drill, on the other hand, is a drill-up or drill-down the hierarchy of a particular

dimension R/OLAPXL recognizes hierarchies within the data warehouse and automatically drills up or down the hierarchy when directed by the user

Consider the following hierarchy in the Product Dimension:

If the report currently displays Product SubGroup and you wish to drill up, R/OLAPXL will drill up to Product Group If you wish to drill down, R/OLAPXL will drill down to Product

Drilling Up Hierarchically

To Drill Up Hierarchically:

Step 1 From the R/OLAPXL menu, click on Drill-Up -or-

On the R/OLAPXL toolbar, click on the Drill-Up button

Step 2

Choose one of the dimensional attributes, then click on the OK command button

R/OLAPXL will drill up the hierarchy to the selected attribute

Drilling Down Hierarchically

Drilling down hierarchically follows the same principle

To Drill Down Hierarchically:

Step 1 From the R/OLAPXL menu, click on Drill-Down -or- On the R/OLAPXL toolbar, click on the Drill-Down button

If more than one dimensional attribute is at a lower level in the hierarchy, R/OLAPXL will present you with a list of fields

Step 2

Choose one of the dimensional attributes, then click on the OK command button

R/OLAPXL will drill down the hierarchy to the selected attribute

Drilling To Hierarchically

R/OLAPXL also comes with a Drill-To option While Drill-Up and Drill-Down drill only one level higher or lower in the dimensional hierarchy, Drill-To allows the user to skip

hierarchical levels

Constraining Your R/OLAPXL Worksheet

Limit the data that R/OLAPXL retrieves from the data warehouse or data mart by using

constraints A constraint is a conditional statement with which any data item must comply

before R/OLAPXL will retrieve it For example, if a business user wishes to see "sales figures for product X, at branch Y, for day Z," the user has actually specified the following constraints:

• Product = "X"

• Branch = "Y"

• Day (or Date) = "Z"

R/OLAPXL recognizes constraints and limits the data that it retrieves so that users get only

the data they need

Constraint Sets in R/OLAPXL

Each R/OLAPXL report starts with no constraints To limit the data retrieved by R/OLAPXL,

you must define one or more Constraint Sets and apply these Constraint Sets to the Facts

in the report

A Constraint Set is any combination of conditions that can be applied to a field in the report You may choose to define these three conditions as one Constraint Set:

• Product = "X"

• Branch = "Y"

• Day (or Date) = "Z"

Each R/OLAPXL fact column can be assigned only one constraint set; however, each

constraint set can have as many conditions as desired

To Create a Constraint Set:

Step 1 From the R/OLAPXL menu, choose Manage Constraint Sets -or-

On the R/OLAPXL toolbar, click on the Manage Constraint Sets button

Step 2

On the pop-up window, click on the New command button Another window will

open

Step 3

On the new pop-up window, you will see the tables of the currently selected schema

on a tree view Name the Constraint Set you wish to create

Note

Be careful when you choose a name for your Constraint Set When the Constraint Set is applied to a column in your report, the Constraint Set name is added to the Column Title

Step 7

On the same pop-up window, select the appropriate operator value Valid values are Equal (=), Less Than (<), Greater Than (>), Less Than or Equal (<=), Greater Than or Equal (>=) and Not Equal (<>), Like, Between, Not Between, In, and Not

In The Like operator can be used only on character fields

Note

The Between operator is typically used on numeric or date attributes (e.g., between

10 and 20, or between year 1997 and year 1998) However, this operator can also

be used on character attributes For example, you may have a constraint for Customer First Name with value BETWEEN A% and B%

Note that the Between operator will not return the maximum value that meets the

constraint For example, if the last customer name that met the constraint value was "Byron Smith," this value will not be returned To obtain a complete list of customers whose first names start with A or B, use the constraint value between A% and C%

Step 8 Enter the value that will be used to constrain the attribute -or-

Click on the List command button to obtain a list of possible values Select one

of the values on the list, then click on the Select command button

Warning

A List command will take a very long time if there are many valid values in the database A classic example is obtaining a list of customers when you have tens or hundreds of thousands of customers in your database

Under such circumstances, you should constrain the list by using the like, between

or in operators

Step 9

Repeat Steps 4 through 7 until all constraints have been defined for the appropriate

attributes Click on the OK command button to define the Constraint Set

Step 10

Click on the New command button to define another Constraint Set, or click on

Close to end

To Assign a Constraint Set:

Step 1 Click on any cell in the column you wish to constrain -or-

Click on the column heading of the column you wish to constrain

Step 2 From the R/OLAPXL menu, choose Assign Constraint Sets -or-

On the R/OLAPXL toolbar, click on the Assign Constraints Sets button A pop-up

window with all defined Constraint Sets will appear

Step 3

Click on the Constraint Set you wish to use

Step 4

Click on the Assign command button The column title will be modified to include

the name of the Constraint Set that was applied

Step 5

You can use the left and right arrows to change the selected column

Step 6

You can also remove a Constraint Set assignment by moving to the appropriate

column, then clicking on the Unassign command button

Step 7

You can change Constraint Sets by selecting a new Constraint Set and assigning it

to the appropriate column The old Constraint Set assignment is overwritten

Step 8

Click on the Close button to end

Note

Only Facts can be assigned Constraint Sets R/OLAPXL will not allow you to assign a

Constraint Set to Dimensional Attributes

To Edit a Constraint Set:

Step 1 From the R/OLAPXL menu, choose Manage Constraint Sets -or-

On the R/OLAPXL toolbar, click on the Manage Constraint Sets button