A Multi-transaction Example

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Go Up to Working with Multiple Transactions


The following C code illustrates the steps required to create a simple multi-transaction program. It declares two transaction handles, mytrans1, and mytrans2, initializes them to zero, starts the transactions, and then uses the transaction names to qualify the data manipulation statements that follow. It also illustrates the use of a cursor with a named transaction.

. . .
EXEC SQL
BEGIN DECLARE SECTION;
long *mytrans1 = 0L, *mytrans2 = 0L;
char city[26];
EXEC SQL
END DECLARE SECTION;
. . .
EXEC SQL
DECLARE CITYLIST CURSOR FOR
SELECT CITY FROM CITIES
WHERE COUNTRY = 'Mexico';
EXEC SQL
SET TRANSACTION NAME mytrans1;
EXEC SQL
SET TRANSACTION mytrans2 READ ONLY READ COMMITTED;
. . .
printf("Mexican city to add to database: ");
gets(city);
EXEC SQL
INSERT TRANSACTION mytrans1 INTO CITIES
VALUES :city, 'Mexico', NULL, NULL, NULL, NULL;
EXEC SQL
COMMIT mytrans1;
EXEC SQL
OPEN TRANSACTION mytrans2 CITYLIST;
EXEC SQL
FETCH CITYLIST INTO :city;
while (!SQLCODE)
{
printf("%s\n", city);
EXEC SQL
FETCH CITYLIST INTO :city;
}
EXEC SQL
CLOSE CITYLIST;
EXEC SQL
COMMIT mytrans2;
EXEC SQL
DISCONNECT
. . .

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