The risnull() function

This sample program is in the risnull.ec file in the demo directory.

/*
   * risnull.ec *

   This program checks the paid_date column of the orders table for NULL
   to determine whether an order has been paid.
*/

#include <stdio.h>

EXEC SQL include sqltypes;

#define WARNNOTIFY          1
#define NOWARNNOTIFY    0

main()
{
    char ans;
    int4 ret, exp_chk();

    EXEC SQL BEGIN DECLARE SECTION;
        int4 order_num;

      mint order_date, ship_date, paid_date;
    EXEC SQL END DECLARE SECTION;

    printf("RISNULL Sample ESQL Program running.\n\n");
    EXEC SQL connect to 'stores7';        /* open stores7 database*/
    exp_chk("CONNECT TO stores7", NOWARNNOTIFY)

    EXEC SQL declare c cursor for
        select order_num, order_date, ship_date, paid_date from orders;
    EXEC SQL open c;
    if(exp_chk("OPEN c", WARNNOTIFY) == 1)  /* Found warnings */
      exit(1);
    printf("\n Order#\tPaid?\n");        /* print column hdgs */
    while(1)
      {
      EXEC SQL fetch c into :order_num, :order_date, :ship_date, :paid_date;
      if ((ret = exp_chk("FETCH c")) == 100)   /* if end of rows */
         break;         /* terminate loop */
      if(ret < 0)
         exit(1);
      printf("%5d\t", order_num);
      if (risnull(CDATETYPE, (char *)&paid_date)) /* is price NULL ? */
         printf("NO\n");
      else
         printf("Yes\n");
      }
   printf("\nRISNULL Sample Program over.\n\n");
}

/*
 *  The exp_chk() file contains the exception handling functions to
 *  check the SQLSTATE status variable to see if an error has occurred
 *  following an SQL statement. If a warning or an error has
 *  occurred, exp_chk() executes the GET DIAGNOSTICS statement and
 *  prints the detail for each exception that is returned.
 */

EXEC SQL include exp_chk.ec