MQRECEIVECLOB

The MQRECEIVECLOB function returns a message from a specified MQSeries® location (return value of CLOB) with removal of the message from the queue.

MQRECEIVECLOB(receive-service,service-policy,correl-id)

The MQRECEIVE function returns a message from the MQSeries location that is specified by receive-service, using the quality-of-service policy that is defined in service-policy. Performing this operation removes the message from the beginning of the queue that is associated with receive-service.

receive-service

An expression that returns a value that is a built-in character string or graphic string data type that is not a LOB. The value of the expression must not be an empty string or a string with trailing blanks. The expression must have an actual length that is no greater than 48 bytes. The value of the expression must refer to a service point that is defined in the SYSIBM.MQSERVICE table. A service point is a logical end-point from where a message is sent or received. Service point definitions include the name of the MQSeries queue manager and queue. For more information about MQSeries Application Messaging, see SQL Programming.

If receive-service is not specified or the null value, DB2®.DEFAULT.SERVICE is used.

service-policy

An expression that returns a value that is a built-in character string or graphic string data type that is not a LOB. The value of the expression must not be an empty string or a string with trailing blanks. The expression must have an actual length that is no greater than 48 bytes. The value of the expression must refer to a service policy that is defined in the SYSIBM.MQPOLICY table. A service policy specifies a set of quality-of-service options that are to be applied to this messaging operation. These options include message priority and message persistence. For more information about MQSeries Application Messaging, see SQL Programming.

If service-policy is not specified or the null value, DB2.DEFAULT.POLICY is used.

correl-id

An expression that returns a value that is a built-in character string or graphic string data type that is not a LOB. The expression must have an actual length that is no greater than 24 bytes. The value of the expression specifies the correlation identifier that is associated with this message. A correlation identifier is often specified in request-and-reply scenarios to associate requests with replies. The first message with a matching correlation identifier is returned. For more information about MQSeries Application Messaging, see SQL Programming.

A fixed length string with trailing blanks is considered a valid value. However, when the correl-id is specified on another request such as MQSEND, the identical correl-id must be specified to be recognized as a match. For example, specifying a value of 'test' for correl-id on MQRECEIVE does not match a correl-id value of 'test ' (with trailing blanks) specified earlier on an MQSEND request.

If correl-id is not specified or is an empty string or the null value, a correlation identifier is not used, and the message at the beginning of the queue is returned.

The result of the function is a CLOB with a length attribute of 2 MB. The result can be null. If no messages are available to be returned, the result is the null value.

The CCSID of the result is the default CCSID at the current server.

Notes

Prerequisites: In order to use the MQSeries functions, IBM® MQSeries for IBM i must be installed, configured, and operational.

Example

This example receives the message at the head of the queue specified by the default service (DB2.DEFAULT.SERVICE), using the default policy (DB2.DEFAULT.POLICY).
```
  SELECT MQRECEIVECLOB ()
   FROM SYSIBM.SYSDUMMY1
   
```
This example receives the message at the head of the queue specified by the service "MYSERVICE" using the default policy (DB2.DEFAULT.POLICY).
```
   SELECT MQRECEIVECLOB ('MYSERVICE')
    FROM SYSIBM.SYSDUMMY1
    
```
This example receives the message at the head of the queue specified by the service "MYSERVICE" using the policy "MYPOLICY".
```
   SELECT MQRECEIVECLOB ('MYSERVICE','MYPOLICY')
    FROM SYSIBM.SYSDUMMY1
    
```
This example receives the first message with a correlation id that matches '1234' from the head of the queue specified by the service "MYSERVICE" using the policy "MYPOLICY".
```
   SELECT MQRECEIVECLOB ('MYSERVICE','MYPOLICY','1234')
    FROM SYSIBM.SYSDUMMY1
    
```