The following example is similar to “Example: Creating a Procedure with Parameters and Local Variables” except that it performs a consume mode SELECT into a queue table. For information about the SELECT AND CONSUME statement, see SQL Data Manipulation Language, B035-1146.
CREATE PROCEDURE spSampleQ(IN ip INTEGER, OUT op INTEGER) BEGIN DECLARE qits TIMESTAMP(6) DEFAULT CURRENT_TIMESTAMP(6), qsn INTEGER GENERATED ALWAYS AS IDENTITY, qcol_1 INTEGER, qcol_2 INTEGER; SELECT AND CONSUME TOP 1 qits, qsn, qcol_1, qcol_2 INTO c_qits, c_qsn, c_qcol_1, c_qcol_2 FROM qtab1e; END;
Note that you must specify an AND CONSUME TOP 1 phrase in your SELECT statement to consume rows from a queue table. The AND CONSUME keywords indicate that the request is a consume mode request, while TOP 1 indicates that the oldest row from the queue table is to be retrieved.