SQL Reference

RELEASE

The RELEASE statement places one or more connections in the release-pending state.

Invocation

Although an interactive SQL facility might provide an interface that gives the appearance of interactive execution, this statement can only be embedded within an application program. It is an executable statement that cannot be dynamically prepared.

Authorization

None Required.

Syntax

                            (1)
>>-RELEASE----+-server-name------+-----------------------------><
              +-host-variable----+
              +-CURRENT----------+
              |    .-SQL-.       |
              '-ALL+-----+-------'
 

Notes:

1. Note that an application server named CURRENT or ALL can only be identified by a host variable.

Description

server-name  or  host-variable

Identifies the application server by the specified server-name or a host-variable which contains the server-name.

If a host-variable is specified, it must be a character string variable with a length attribute that is not greater than 8, and it must not include an indicator variable. The server-name that is contained within the host-variable must be left-justified and must not be delimited by quotation marks.

Note that the server-name is a database alias identifying the application server. It must be listed in the application requester's local directory.

The specified database-alias or the database-alias contained in the host variable must identify an existing connection of the application process. If the database-alias does not identify an existing connection, an error (SQLSTATE 08003) is raised.

CURRENT

Identifies the current connection of the application process. The application process must be in the connected state. If not, an error (SQLSTATE 08003) is raised.

ALL

Identifies all existing connections of the application process. This form of the RELEASE statement places all existing connections of the application process in the release-pending state. All connections will therefore be destroyed during the next commit operation. An error or warning does not occur if no connections exist when the statement is executed. The optional keyword SQL is included to be compatible with DB2/MVS SQL syntax.

Notes

• If the RELEASE statement is successful, the identified connection is placed in the release-pending state and will therefore be destroyed during the next commit operation.

  If the RELEASE statement is unsuccessful, the connection state of the application process and the states of its connections are unchanged.

• If the current connection is in the release-pending state when a commit operation is performed, the destruction of that connection places the application process into the unconnected state. In this case, the next executed SQL statement should be CONNECT or SET CONNECTION.

• Type 1 CONNECT semantics do not preclude the use of RELEASE. The connection will be disconnected when the unit of work is committed.

• RELEASE does not close cursors, does not release any resources, and does not prevent further use of the connection.

• A rollback operation does not reset the state of a connection from release-pending to held.

• Resources are required to create and maintain remote connections. Thus, a remote connection that is not going to be reused should be destroyed as soon as possible.

• Connections can also be destroyed during a commit operation because the option DISCONNECT(AUTOMATIC) or the option DISCONNECT(CONDITIONAL) is in effect. See Options that Govern Distributed Unit of Work Semantics for information about the specification of the DISCONNECT option.

Examples

Example 1:  The SQL connection to IBMSTHDB is no longer needed by the application. The following statement will cause it to be destroyed during the next commit operation:

   EXEC SQL RELEASE IBMSTHDB;

Example 2:  The current connection is no longer needed by the application. The following statement will cause it to be destroyed during the next commit operation:

   EXEC SQL RELEASE CURRENT;

Example 3:  If an application has no need to access the databases after a commit but will continue to run for a while, then it is better not to tie up those connections unnecessarily. The following statement can be executed before the commit to ensure all connections will be destroyed at the commit:

   EXEC SQL RELEASE ALL;

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