SQL Statements

ALTER DATABASE

ALTER DATABASE database_name;

ALTER DATABASE command changes the size or settings of a database. Its syntax varies widely among different database systems.

ALTER USER

ALTER USER user

ALTER USER statement changes a user's system settings such as password.

BEGIN TRANSACTION

1> BEGIN TRANSACTION transaction_name

2> transaction type

3> if exists

4> begin

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

CLOSE cursor_name statement closes the cursor and clears it of data. To completely remove the cursor, use the DEALLOCATE CURSOR statement.

COMMIT TRANSACTION

SQL> COMMIT;

COMMIT TRANSACTION statement saves all work begun since the beginning of the transaction (since the BEGIN TRANSACTION statement was executed).

CREATE DATABASE

SQL> CREATE DATABASE database_name;

database_name 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], ...);

the contents of the indexed field(s).

CREATE PROCEDURE

create procedure procedure_name

   [[(]@parameter_name

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

     [= default][output]

   [, @parameter_name

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

     [= default][output]]...[)]]

   [with recompile]

   as SQL_statements

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 input and output parameters passing 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 ]...)

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.

CREATE TRIGGER

create trigger trigger_name

  on table_name

  for {insert, update, delete}

  as SQL_Statements

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

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>

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

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

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;

DROP DATABASE statement completely deletes a database, including all data and the database's physical structure on disk.

DROP INDEX

DROP INDEX index_name;

DROP INDEX statement removes an index from a table.

DROP PROCEDURE

drop procedure procedure_name

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;

DROP TABLE statement drops a table from a database.

DROP TRIGGER

DROP TRIGGER trigger_name

DROP TRIGGER statement removes a trigger from a database.

DROP VIEW

DROP VIEW view_name;

DROP VIEW statement removes a view from a database.

EXECUTE

execute [@return_status = ]

   procedure_name

   [[@parameter_name =] value |

     [@parameter_name =] @variable [output]...]]

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]

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> ...]

FROM specifies which tables are used and/or joined.

GRANT

GRANT role TO user

or

GRANT system_privilege TO {user_name | role | PUBLIC}

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> ...]

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

HAVING

HAVING <search_cond>

HAVING is valid only with GROUP BY and limits the selection of groups to those that satisfy the search condition.

INTERSECT

INTERSECT

INTERSECT returns all the common elements of two SELECT statements.

ORDER BY

ORDER BY <order_list>

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

ROLLBACK TRANSACTION

ROLLBACK TRANSACTION statement effectively cancels all work done within a transaction (since the BEGIN TRANSACTION statement was executed).

REVOKE

REVOKE role FROM user;

or

REVOKE {object_priv | ALL [PRIVILEGES]}

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

ON [schema.]object

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

REVOKE command removes a database privilege from a user, whether it be a system privilege or a role.

SELECT

SELECT [DISTINCT | ALL]

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

SQL> SET TRANSACTION (READ ONLY | USE ROLLBACK SEGMENT);

SET TRANSACTION 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

UNION statement returns all the elements of two SELECT statements.

WHERE

WHERE <search_cond>

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

*

* gets all the columns of a particular table.