cs_setnull

Description

Defines a null substitution value to be used when binding or converting NULL data.

Syntax

CS_RETCODE cs_setnull(context, datafmt, buffer,
                 buflen)
 
 CS_CONTEXT      *context;
 CS_DATAFMT      *datafmt;
 CS_VOID           *buffer;
 CS_INT              buflen;

Parameters

Returns

cs_set_null returns:

Common reasons for a cs_setnull failure include:

• A memory allocation error

• An invalid parameter

Usage

• If ANSI-style binds are in effect, CS-Library does not use null substitution values. To activate ANSI-style binds, an application sets the Client-Library property CS_ANSI_BINDS to CS_TRUE.

• When ANSI-style binds are not in effect and source data for a conversion is NULL, CS-Library sets the destination data to the predefined null substitution value for that destination type. For example, converting a NULL value of any type to a CS_CHAR destination results in an empty string.

• In a Client-Library application, null substitution values are defined at the context level. When a Client-Library connection is allocated, it picks up null substitution values from its parent context.

• When converting a NULL source value to a CS_CHAR or CS_BINARY destination variable, CS-Library first puts 0 bytes into the destination and then uses the format field of the CS_DATAFMT structure that describes the destination to determine whether to pad or null-terminate.

• To reinstate CS-Library’s original default null substitution value for a particular datatype, an application can call cs_setnull with buffer as NULL.

• CS-Library and Client-Library use the following default null substitution values:

See also