The rsetnull() function

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

/*
   * rsetnull.ec *

   This program fetches rows from the stock table for a chosen manufacturer
   and allows the user to set the unit_price to NULL.
*/

#include <stdio.h>
#include <ctype.h>
EXEC SQL include decimal;
EXEC SQL include sqltypes;

#define WARNNOTIFY      1
#define NOWARNNOTIFY    0

#define LCASE(c) (isupper(c) ? tolower(c) : (c))

char format[] = "($$,$$$,$$$.&&)";

main()
{
   char decdsply[20];
   char ans;
   int4 ret, exp_chk();

   EXEC SQL BEGIN DECLARE SECTION;
      short stock_num;
      char description[16];
      dec_t unit_price;
      char manu_code[4];
   EXEC SQL END DECLARE SECTION;

    printf("RSETNULL Sample ESQL Program running.\n\n");
    EXEC SQL connect to 'stores7';        /* connect to stores7 */
    exp_chk("Connect to stores7", NOWARNNOTIFY);

    printf("This program selects all rows for a given manufacturer\n");
    printf("from the stock table and allows you to set the unit_price\n");
    printf("to NULL.\n");
    printf("\nTo begin, enter a manufacturer code - for example: 'HSK'\n");
    printf("\nEnter Manufacturer code: ");        /* prompt for mfr. code */
    gets(manu_code);            /* get mfr. code */
    EXEC SQL declare upcurs cursor for       /* declare cursor */
      select stock_num, description, unit_price from stock
      where manu_code = :manu_code
      for update of unit_price;
    rupshift(manu_code);        /* Make mfr code upper case */
    EXEC SQL open upcurs;  /* open select cursor */
    if(exp_chk("Open cursor", WARNNOTIFY) == 1)
      exit(1);

    /*
    * Display Column Headings
     */
    printf("\nStock # \tDescription \t\tUnit Price");
    while(1)
      {
      /* get a row */
      EXEC SQL fetch upcurs into :stock_num, :description, :unit_price;
      if ((ret = exp_chk("fetch", WARNNOTIFY)) == 100)  /* if end of rows */
         break;
      if(ret == 1)
         exit(1);
      if(risnull(CDECIMALTYPE, (char *) &unit_price))  /* unit_price NULL? */
         continue;            /* skip to next row */
      rfmtdec(&unit_price, format, decdsply); /* format unit_price */
      /* display item */
      printf("\n\t%d\t%15s\t%s", stock_num, description, decdsply);
      ans = ' ';
      /* Set unit_price to NULL? y(es) or n(o) */
      while((ans = LCASE(ans)) != 'y' && ans != 'n')
         {
         printf("\n. . . Set unit_price to NULL ? (y/n) ");
         scanf("%1s", &ans);
         }
      if (ans == 'y')                  /* if yes, NULL to unit_price */
         {
         rsetnull(CDECIMALTYPE, (char *) &unit_price);
         EXEC SQL update stock set unit_price = :unit_price
            where current of upcurs;        /* and update current row */
         if(exp_chk("UPDATE", WARNNOTIFY) == 1)
            exit(1);
         }
      }
   printf("\nRSETNULL 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