Category Archives: SQL

SQL Glossary of Common SQL Commands

SQL Glossary of Common SQL Commands

*

The asterisk character returns all the columns of a particular table.

ALTER DATABASE

ALTER DATABASE database_name;

The ALTER DATABASE statement changes the size or settings of a database.

Its syntax varies widely among different database systems.

ALTER USER

ALTER USER user

The ALTER USER statement changes a user’s system settings such as a

password.

BEGIN TRANSACTION

1> BEGIN TRANSACTION transaction_name

2> transaction type

3> if exists

4> begin

The BEGIN TRANSACTION statement signifies the beginning of a user transaction.

A transaction ends when it is either committed (see COMMIT TRANSACTION)

or canceled (see ROLLBACK TRANSACTION). A transaction is a logical

unit of work.

CLOSE CURSOR

close cursor_name

The CLOSE cursor_name statement closes the cursor and clears it of data. To

completely remove the cursor, use the DEALLOCATE CURSOR statement.

COMMIT TRANSACTION

COMMIT;

The COMMIT TRANSACTION statement saves all work since the beginning of the transaction

(since the BEGIN TRANSACTION statement was executed).

CREATE DATABASE

CREATE DATABASE database_name;

The CREATE DATABASE statement creates a new database. Many different options can be

supplied, such as the device on which to create the database and the size of the initial

database.

CREATE INDEX

CREATE INDEX index_name

ON table_name(column_name1, [column_name2], …);

An index can order the contents of a table based on the contents of the indexed field(s).

CREATE PROCEDURE

CREATCCREATE PROCEDURE procedure_name

[[(]@parameter_name

datatype [(length)
| (precision [, scale])

[= default][output]

[, @parameter_name

datatype [(length)
| (precision [, scale])

[= default][output]]…[)]]

[with recompile]

AS SQL_statements

The CREATE PROCEDURE statement creates a new stored procedure in the database. This

stored procedure can consist of SQL statements and can then be executed using the

EXECUTE command. Stored procedures support the passing of input and output parameters

and can return an integer value for status checking.

CREATE TABLE

CREATE TABLE table_name

( field1 datatype [ NOT NULL ],

field2 datatype [ NOT NULL ],

field3 datatype [ NOT NULL ]…)

The CREATE TABLE statement creates a new table within a database. Each optional field is

provided with a name and data type for creation within that table.

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CREATE TRIGGER

CREATE TRIGGER trigger_name

ON table_name

FOR {insert, update, delete}

AS SQL_Statements

The CREATE TRIGGER statement creates a trigger object in the database that will execute

its SQL statements when its corresponding table is modified through an INSERT, UPDATE,

or DELETE. Triggers can also call stored procedures to execute complex tasks.

CREATE USER

CREATE USER user

The CREATE USER statement creates a new user account, complete with user ID and

password.

CREATE VIEW

CREATE VIEW <view_name> [(column1,
column2…)] AS

SELECT <table_name column_names>

FROM <table_name>

A view is often described as a virtual table. Views are created by using the CREATE VIEW

statement. After a view is created, it can be queried, and data within the view can be

modified.

DEALLOCATE CURSOR

DEALLOCATE CURSOR cursor_name

The DEALLOCATE CURSOR statement completely removes the cursor from memory and

frees the name for use by another cursor. You should always close the cursor with the

CLOSE CURSOR statement before deallocating it.

DECLARE CURSOR

DECLARE cursor_name CURSOR

FOR select_statement

The DECLARE CURSOR statement creates a new cursor from the SELECT statement query.

The FETCH statement scrolls the cursor through the data until the variables have been

loaded. Then the cursor scrolls to the next record.

DROP DATABASE

DROP DATABASE database_name;

Glossary of Common SQL Commands PDF:3

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The DROP DATABASE statement completely deletes a database, including all data and the

database’s physical structure on disk.

DROP INDEX

DROP INDEX index_name;

The DROP INDEX statement removes an index from a table.

DROP PROCEDURE

DROP PROCEDURE procedure_name

The DROP PROCEDURE statement drops a stored procedure from the database; its function

is similar to the DROP TABLE and DROP INDEX statements.

DROP TABLE

DROP TABLE table_name;

The DROP TABLE statement drops a table from a database.

DROP TRIGGER

DROP TRIGGER trigger_name

The DROP TRIGGER statement removes a trigger from a database.

DROP VIEW

DROP VIEW view_name;

The DROP VIEW statement removes a view from a database.

EXECUTE

EXECUTE [@return_status = ]

procedure_name

[[@parameter_name
=] value |

[@parameter_name
=] @variable [output]…]]

The EXECUTE command runs a stored procedure and its associated SQL statements.

Parameters can be passed to the stored procedure, and data can be returned in these

parameters if the OUTPUT keyword is used.

FETCH

FETCH cursor_name [into fetch_target_list]

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The FETCH command loads the contents of the cursor’s data into the provided program

variables. After the variables have been loaded, the cursor scrolls to the next record.

FROM

FROM <tableref> [, <tableref> …]

The FROM statement specifies which tables are used and/or joined.

GRANT

GRANT role TO user

or

GRANT system_privilege TO {user_name | role | PUBLIC}

The GRANT command grants a privilege or role to a user who has been created using the

CREATE USER command.

GROUP BY

GROUP BY <col> [, <col> …]

The GROUP BY statement groups all the rows with the same column value.

HAVING

HAVING <search_cond>

The HAVING statement is valid only with GROUP BY and limits the selection of groups to

those that satisfy the search condition.

INTERSECT

INTERSECT

The INTERSECT statement returns all the common elements of two SELECT statements.

ORDER BY

ORDER BY <order_list>

The ORDER BY statement orders the returned values by the specified column(s).

REVOKE

REVOKE role FROM user;

Glossary of Common SQL Commands PDF:5

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or

REVOKE {object_priv | ALL [PRIVILEGES]}

[, {object_priv
|
ALL [PRIVILEGES]} ] …

ON [schema.]object

FROM {user | role | PUBLIC} [, {user
|
role |
PUBLIC}] …

The REVOKE command removes a database privilege from a user, whether it be a system

privilege or a role.

ROLLBACK TRANSACTION

ROLLBACK TRANSACTIONROLLBAKC;

The ROLLBACK TRANSACTION statement effectively cancels all work done within a transaction

(since the BEGIN TRANSACTION statement was executed).

SELECT

SELECT [DISTINCT
| ALL]

The SELECT statement is the beginning of each data retrieval statement. The modifier

DISTINCT specifies unique values and prevents duplicates. ALL is the default and allows

duplicates.

SET TRANSACTION

SET TRANSACTION (READ ONLY | USE ROLLBACK SEGMENT);

The SET TRANSACTION command enables the user to specify when a transaction should

begin. The READ ONLY option locks a set of records until the transaction ends to ensure

that the data is not changed.

UNION

UNION

The UNION statement returns all the elements of two SELECT statements.

WHERE

WHERE <search_cond>

The WHERE statement limits the rows retrieved to those meeting the search condition.