ASA Programming Guide
  ODBC Programming
    Connecting to a data source

Establishing a connection

Your application must establish a connection before it can carry out any database operations.

To establish an ODBC connection

1. Allocate an ODBC environment.

   For example:

   SQLHENV   env;
   SQLRETURN retcode;
   retcode = SQLAllocHandle( SQL_HANDLE_ENV,
     SQL_NULL_HANDLE, &env );

2. Declare the ODBC version.

   By declaring that the application follows ODBC version 3, SQLSTATE values and some other version-dependent features are set to the proper behavior. For example:

   retcode = SQLSetEnvAttr( env,
     SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0);

3. If necessary, assemble the data source or connection string.

   Depending on your application, you may have a hard-coded data source or connection string, or you may store it externally for greater flexibility.

4. Allocate an ODBC connection item.

   For example:

   retcode = SQLAllocHandle( SQL_HANDLE_DBC, env, &dbc );

5. Set any connection attributes that must be set before connecting.

   Some connection attributes must be set before establishing a connection, while others can be set either before or after. For example:

   retcode = SQLSetConnectAttr( dbc,
      SQL_AUTOCOMMIT, 
      (SQLPOINTER)SQL_AUTOCOMMIT_OFF, 0 );

   For more information, see Setting connection attributes.

6. Call the ODBC connection function.

   For example:

   if (retcode == SQL_SUCCESS 
       || retcode == SQL_SUCCESS_WITH_INFO) {
      printf( "dbc allocated\n" );
      retcode = SQLConnect( dbc,
         (SQLCHAR*) "ASA 9.0 Sample", SQL_NTS,
         (SQLCHAR* ) "DBA", SQL_NTS,
         (SQLCHAR*) "SQL", SQL_NTS );
      if (retcode == SQL_SUCCESS
            || retcode == SQL_SUCCESS_WITH_INFO){
      // successfully connected.

You can find a complete sample as Samples\ASA\ODBCConnect\odbcconnect.cpp in your SQL Anywhere directory.

Notes 

• SQL_NTS    Every string passed to ODBC has a corresponding length. If the length is unknown, you can pass SQL_NTS indicating that it is a Null Terminated String whose end is marked by the null character (\0).

• SQLSetConnectAttr    By default, ODBC operates in auto-commit mode. This mode is turned off by setting SQL_AUTOCOMMIT to false.

  For more information, see Setting connection attributes.