FairCom ISAM for C

getIDfield

Return IDENTITY attribute information from a file.

Declaration

NINT getIDfield(FILNO datno, NINT mode, pLONG8 retval)

Description

In V12 the file number typedef was formally changed from COUNT, a two-byte value to FILNO, a four-byte value. Refer to this link for compatibility details. Four Byte File Numbering

getIDfield() returns information about an IDfield (IDENTITY) value.

Where:

datno is the data file number
mode is the next value to be assigned to the field on add.
retval is the value to increment each addition.

mode can take one of the following values:

updateValue - return is set to the next IDfield value, and the IDfield is updated
reportValue - return is set to the next IDfield value, but the IDfield remains unchanged
startingValue - return is set to the starting value for the IDfield
deltaValue - return is set to the IDfield change value (delta in IDfield)

IDfield requires a DAR resource (Direct Access Resource) embedded in the file. The DAR is a specialized high-speed resource.

Return

Value	Symbolic Constant	Explanation
0	NO_ERROR	Success

See FairCom DB Error Codes for a complete listing of valid FairCom DB error values.

Example

retval = getIDfield(fileno, reportValue, &idval);

if (retval) {

printf("\tERROR: Failed to retrieve ID information with error %d\n", retval);

}

else

printf("Next IDENTITY value is %d\n", idval);

Override IDENTITY Values

PUTHDR() using the ctIDfieldOverRide mode can turn on and off the ability to override the automatic IDfield values. The override is on a per user, per file basis. A nonzero hdrval turns on the override, and a zero hdrval restores the standard operation. When the override is on for a data file that supports an IDfield, then an add record operation does not fill-in the IDfield value. Whatever is passed in the record buffer is used for the IDfield. And a rewrite permits the IDfield value to change instead of generating the IDFL_CHG error. When the override is enabled, add record operations do not consume IDfield values.