**Table 3-43: Environment variables (srv_envchange)**
Changing value	Message number	#define in oserror.h
Current Database	5701	SQLSRV_ENVDB
National Language	5703	SQLSRV_ENVLANG

srv_envchange

Description

Notify the client of an environment change.

Syntax

CS_RETCODE srv_envchange(spp, type, oldvalp
            oldvallen, newvalp, newvallen)

SRV_PROC    *spp;
CS_INT          type;
CS_CHAR     *oldvalp;
CS_INT         oldvallen
CS_CHAR     *newvalp;
CS_INT         newvallen

Parameters

spp: A pointer to an internal thread control structure.

type: The environment being changed. Currently, the only legal values are SRV_ENVDATABASE and SRV_ENVLANG, the name of the current database and the current national language, respectively.

oldvalp: A pointer to the character string containing the old value. It can be NULL. Its length in bytes is stored in oldvallen.

oldvallen: The length, in bytes, of the string in *oldvalp. It can be CS_NULLTERM, which indicates that the string in *oldvalp is null terminated. It can also be CS_UNUSED, indicating that the string in *oldvalp is NULL.

newvalp: A pointer to the character string containing the new value of the environment variable. It can be null. Its length in bytes is stored in newvallen.

newvallen: The length, in bytes, of the string in *newvalp. It can be CS_NULLTERM, which indicates that the string in newvalp is null terminated. It can also be CS_UNUSED, indicating that the string in *newvalp is NULL.

Returns

**Table 3-42: Return values (srv_envchange)**
Returns	To indicate
CS_SUCCEED	The routine completed successfully.
CS_FAIL	The routine failed.

Examples

Example 1

#include   <ospublic.h>

/*

 ** Local Prototype.

*/

CS_RETCODE  ex_srv_envchange PROTOTYPE((

SRV_PROC    *spp

));

/*

 ** EX_SRV_ENVCHANGE

**

**    Example routine to notify the client of an environment

 **    change.

**

** Arguments:

**    spp    A pointer to an internal thread control structure.

**

** Returns:

**     CS_SUCCEED    Succesfully notified client of environment

 **                   change.

**     CS_FAIL       An error was detected.

**

*/

CS_RETCODE   ex_srv_envchange(spp)

SRV_PROC     *spp;

    CS_RETCODE   retval;

/*

     ** Notify the client that we’ve changed the database

     ** from “master” to “pubs2”.

*/

    retval = srv_envchange(spp, SRV_ENVDATABASE, “master”,

             CS_NULLTERM, “pubs2”, CS_NULLTERM);

    return (retval);

Usage

There are various environment variables which can be set. Open Server handles some automatically, while others must be handled by an Open Server application. Currently, an application can only inform a client of a change to the current database or national language.

Open Server calls an Open Server application’s error handler any time one of the values changes. An Open Server application can change it through srv_envchange, or Open Server can change it using internal code, or both. The error number passed to the error handler is the Adaptive Server message number sent back to a client when one of these values changes. This allows a client application to match the same message number to a changing value, whether the client is connected to an Open Server or an Adaptive Server. Table 3-43 lists the message number and oserror.h #define that correspond to each changing value.

Table 3-43: Environment variables (srv_envchange)
Changing value

Message number

#define in oserror.h

Current Database

5701

SQLSRV_ENVDB

National Language

5703

SQLSRV_ENVLANG