Oracle Database 10g SQL Fundamentals pps

Join StatementsSelf Join SELECT FROM table alias1, table alias2 WHERE alias1.col1 = alias2.col2 1-17 Bản quyền thuộc COMMIT., JSC... DML Statements• MERGE INTO table1 USING table2 ON co

Bản quyền thuộc COMMIT., JSC.

Oracle Database 10g:

SQL Fundamentals – Review

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SQL Statements

• SELECT

• Data Manipulation Language – DML

• Transaction Control Language – TCL

• Data Definition Language – DDL

• Data Control Language – DCL

Single-Row Functions Character Functions

Single-Row Functions Number Functions

• ROUND(col|expr, [n])

• TRUNC(col|expr, [n])

• MOD(m, n)

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Single-Row Functions Conversion Functions

Single-Row Functions General Functions

CASE Expression

– CASE expr

– WHEN comparison_expr1 THEN return_expr1

– [WHEN comparison_expr2 THEN return_expr2

–

– WHEN comparison_exprn THEN return_exprn

– ELSE return_expr]

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Join Statements Natural Join

FROM table1, table2

WHERE table1.col1[(+)] = table2.col2[(+)]

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Join Statements

Self Join

SELECT <select_clause>

FROM table alias1, table alias2

WHERE alias1.col1 = alias2.col2

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• Classification

– Single-row

– Multiple-row

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Multiple-row Subquery

• Return more than one row

• Operator

IN ALL ANY

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Top-N Analysis

• Syntax

SELECT ROWNUM, [column_list]

FROM (SELECT [column_list]

FROM tableORDER BY top-N_column ASC|DESC)WHERE ROWNUM <= N;

• Notes:

– ROWNUM: assigns a sequential value starting with 1 to each of the rows returned from the query

– A WHERE clause specifies the n rows to be returned The

comparison operator must be < or <=

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DML Statements

• MERGE INTO table1

USING table2 ON (condition)

WHEN MATCHED THEN

UPDATE SET

column = value [, column = value…]

DELETE WHERE conditions WHEN NOT MATCHED THEN

INSERT [(column_list)]

VALUES (value_list)

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Creating/Dropping Table

• CREATE TABLE table_name

(column datatype [DEFAULT default_val]

Altering Table Add Columns

• ALTER TABLE table ADD

(column datatype [DEFAULT default_val]

[col_lvl_constraints]

[, column datatype [DEFAULT default_val]

[col_lvl_constraints]…])

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Altering Table – Modify Column

• ALTER TABLE table MODIFY

(column datatype [DEFAULT default_val]

[col_lvl_constraints]…)

• ALTER TABLE table

RENAME COLUMN old_name TO new_name

• Datatype of any column can be changed if all rows of the column contain nulls

• Size of a character/raw column or the precision of a

numeric column can always be increased

• Size of a datatype of a column can be reduced as long as the change does not require data to be modified

• Datatype of a column can be changed from CHAR/VARCHAR2 to VARCHAR2/CHAR only if all rows of the column contain nulls

or do not change the size

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Altering Table – Drop Column

• ALTER TABLE table SET UNUSED COLUMN column

• ALTER TABLE table DROP UNUSED COLUMNS

• ALTER TABLE table DROP COLUMNS CONTINUE

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Altering Table – Add/Drop Constraint

• ALTER TABLE table_name ADD

[[CONSTRAINT cons_name] cons_def ]

• ALTER TABLE table_name

DROP CONSTRAINT cons_name [CASCADE]

• ALTER TABLE table

DROP (constraint_list) [CASCADE]

• ALTER TABLE table

DROP PRIMARY KEY [CASCADE]

• ALTER TABLE table

DROP UNIQUE (column_list) [CASCADE]

• When dropping PRIMARY KEY and UNIQUE constraint, the corresponding index will be dropped

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Altering Table Enable/Disable Constraint

• ALTER TABLE table

DISABLE CONSTRAINT constraint [CASCADE]

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– WITH CHECK OPTION: Ensure INSERTs and UPDATEs

operations performed on through the view cannot create/modify rows that the view cannot select

– WITH READ ONLY: Prevent DML operations occur on views

• Drop view

DROP VIEW view_name

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– Unique/Nonunique Index: Specify UNIQUE to indicate that the

value of the column (or columns) upon which the index is based must be unique

– Composite: An index that is created based on multiple columns– Function-based index: An index that is created based on the value

of an expression

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Managing Synonym

• Syntax:

– CREATE [PUBLIC] SYNONYM synonym FOR object;

– DROP SYNONYM synonym;

• Notes:

– PUBLIC: create a synonym that is accessible to all users

– Private synonym name must be distinct from all other objects that owned by the same user

– If a public synonym has same name with an object in an user’s schema, his object will be used prior to public synonym

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Renaming Objects

• Syntax:

– RENAME old_name TO new_name;

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Controlling Access

• Grant roles or system privileges

GRANT role|sys_priv [, role|sys_priv ]

TO user|role [, user|role ] [WITH ADMIN OPTION]

• Grant object privileges

GRANT obj_priv [, obj_priv ]

ON object[(column_list)]

TO user|role [, user|role ] [WITH GRANT OPTION]

• Revoke system privileges

REVOKE role|sys_priv [, role|sys_priv ]

FROM user|role [, user|role ]

• Revoke object privileges

REVOKE {obj_priv [(column_list)]}

ON object

FROM user|role [, user|role ] [CASCADE CONSTRAINT]

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