AdsIsNull

Tests whether a field in the current record is NULL.

Syntax

UNSIGNED32 AdsIsNull(ADSHANDLE hTable, UNSIGNED8 *pucField,
                      UNSIGNED16 *pbNull);

Parameters

Parameter	Type	Description
`hTable`	`ADSHANDLE`	Handle of the table (local, remote, or backend).
`pucField`	`UNSIGNED8*`	Field name (NUL-terminated string) or 1-based ordinal via `ADSFIELD(n)`.
`pbNull`	`UNSIGNED16*`	Output — `1` if the field is NULL, `0` otherwise.

Return Value

AE_SUCCESS (0) on success. Non-zero error code on failure (invalid handle, field not found).

Description

AdsIsNull inspects the NULL bitmap of the current record to determine whether the specified field is NULL. The NULL bitmap is only present in ADT tables; for CDX/NTX tables it is always absent, so the function always reports “not null” (0).

For remote and backend tables the function conservatively reports “not null” since NULLability isn’t exposed over the wire protocol yet.

Example

ADSHANDLE hTable;
UNSIGNED16 isNull = 0;
AdsOpenTable(&hTable, "customers.adt", NULL, NULL,
             ADS_ANSI, ADS_EXCLUSIVE, NULL, NULL);
AdsGotoTop(hTable);
AdsIsNull(hTable, (UNSIGNED8*)"email", &isNull);
if (isNull)
    printf("email is NULL\n");
else
    printf("email has a value\n");
AdsCloseTable(hTable);