SQL/MX Queuing and Publish/Subscribe Services

Embedded SQL Examples
HP NonStop SQL/MX Queuing and Publish/Subscribe Services—523734-002
3-3
Embedded DELETE
Embedded DELETE
Embedded DELETE statements enable applications to read and delete rows with a
single operation. This example shows the use of an embedded DELETE with stream
access and a holdable cursor. Note that after each fetch, the application commits its
transaction and starts a new transaction before looping to fetch again.
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#include <stdio.h>
#include <string.h>
long EmbeddedDelete()
{
EXEC SQL BEGIN DECLARE SECTION;
int destination;
int origin;
int seqnbr;
long SQLCODE;
EXEC SQL END DECLARE SECTION;
EXEC SQL WHENEVER SQLERROR GOTO EndOfProcessing;
/* Dequeue and route incoming parcels to next destination */
EXEC SQL DECLARE arrivals CURSOR WITH HOLD FOR
SELECT destination, origin, seqnbr
FROM (DELETE FROM STREAM(inbox)) AS inbox;
EXEC SQL BEGIN WORK; /* Start transaction */
EXEC SQL OPEN arrivals;
/* Wait for newly arrived parcels and notify receivers */
while (1) {
/* Dequeue notifications */
EXEC SQL FETCH arrivals
INTO :destination,:origin,:seqnbr;
printf("\nDestination:%d Origin:%d "
"Sequence number:%d",
destination, origin, seqnbr);
/* Route package and notify receivers
routePackage(seqnbr, destination, origin);
EXEC SQL COMMIT WORK; /* Commit transaction */
EXEC SQL BEGIN WORK; /* Start new transaction */
}
EndOfProcessing:
EXEC SQL WHENEVER SQLERROR GOTO EndError;
EXEC SQL CLOSE arrivals;
EndError:
return SQLCODE;
}
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