Types of SQL Statements

The tables in the following sections provide a functional summary of SQL statements and are divided into these categories:

• Data definition language (DDL) statements
• Data manipulation language (DML) statements
• Transaction control statements
• Session control statements
• System control statements

Data Definition Language (DDL) Statements

Data definition language (DDL) statements enable you to perform these tasks:

• Create, alter, and drop schema objects
• Grant and revoke privileges and roles
• Analyze information on a table, index, or cluster
• Establish auditing options
• Add comments to the data dictionary

The CREATE, ALTER, and DROP commands require exclusive access to the specified object. For example, an ALTER TABLE statement fails if another user has an open transaction on the specified table.

The GRANT, REVOKE, ANALYZE, AUDIT, and COMMENT commands do not require exclusive access to the specified object. For example, you can analyze a table while other users are updating the table.

Oracle implicitly commits the current transaction before and after every DDL statement.

Many DDL statements may cause Oracle to recompile or reauthorize schema objects. For information on how Oracle recompiles and reauthorizes schema objects and the circumstances under which a DDL statement would cause this, see Oracle9i Database Concepts.

DDL statements are supported by PL/SQL with the use of the DBMS_SQL package.

The DDL statements are:

ALTER ... (All statements beginning with ALTER)

ANALYZE

ASSOCIATE STATISTICS

AUDIT

COMMENT

CREATE ... (All statements beginning with CREATE)

DISASSOCIATE STATISTICS

DROP ... (All statements beginning with DROP)

GRANT

NOAUDIT

RENAME

REVOKE

TRUNCATE

Data Manipulation Language (DML) Statements

Data manipulation language (DML) statements query and manipulate data in existing schema objects. These statements do not implicitly commit the current transaction. The data manipulation language statements are:

CALL

DELETE

EXPLAIN PLAN

INSERT

LOCK TABLE

MERGE

SELECT

UPDATE

The CALL and EXPLAIN PLAN statements are supported in PL/SQL only when executed dynamically. All other DML statements are fully supported in PL/SQL.

Transaction Control Statements

Transaction control statements manage changes made by DML statements. The transaction control statements are:

COMMIT

ROLLBACK

SAVEPOINT

SET TRANSACTION

All transaction control statements, except certain forms of the COMMIT and ROLLBACK commands, are supported in PL/SQL. For information on the restrictions, see COMMIT and ROLLBACK.

Session Control Statements

Session control statements dynamically manage the properties of a user session. These statements do not implicitly commit the current transaction.

PL/SQL does not support session control statements. The session control statements are:

ALTER SESSION

SET ROLE

System Control Statement

The single system control statement, ALTER SYSTEM, dynamically manages the properties of an Oracle instance. This statement does not implicitly commit the current transaction and is not supported in PL/SQL.

Embedded SQL Statements

Embedded SQL statements place DDL, DML, and transaction control statements within a procedural language program. Embedded SQL is supported by the Oracle precompilers and is documented in the following books:

• Pro*COBOL Precompiler Programmer's Guide
• Pro*C/C++ Precompiler Programmer's Guide
• SQL*Module for Ada Programmer's Guide