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Process Return Codes and Output Parameters (ODBC)

SQL Server stored procedures can have integer return codes and output parameters. The return codes and output parameters are sent in the last packet from the server and are not available to the application until SQLMoreResults returns SQL_NO_DATA. If an error is returned from a stored procedure, call SQLMoreResults to advance to the next result until SQL_NO_DATA is returned.

Security note Security Note

When possible, use Windows Authentication. If Windows Authentication is not available, prompt users to enter their credentials at run time. Avoid storing credentials in a file. If you must persist credentials, you should encrypt them with the Win32 crypto API.

To process return codes and output parameters

  1. Construct an SQL statement that uses the ODBC CALL escape sequence. The statement should use parameter markers for each input, input/output, and output parameter, and for the procedure return value (if any).

  2. Call SQLBindParameter for each input, input/output, and output parameter, and for the procedure return value (if any).

  3. Execute the statement with SQLExecDirect.

  4. Process result sets until SQLFetch or SQLFetchScroll returns SQL_NO_DATA while processing the last result set or until SQLMoreResults returns SQL_NO_DATA. At this point, the variables bound to the return code and output parameters are filled with returned data values.

This sample shows processing a return code and output parameter. This sample is not supported on IA64. This sample was developed for ODBC version 3.0 or later.

You will need an ODBC data source called AdventureWorks, whose default database is the AdventureWorks sample database. (You can download the AdventureWorks sample database from the Microsoft SQL Server Samples and Community Projects home page.) This data source must be based on the ODBC driver that is supplied by the operating system (the driver name is "SQL Server"). If you will build and run this sample as a 32-bit application on a 64-bit operating system, you must create the ODBC data source with the ODBC Administrator in %windir%\SysWOW64\odbcad32.exe.

This sample connects to your computer's default SQL Server instance. To connect to a named instance, change the definition of the ODBC data source to specify the instance using the following format: server\namedinstance. By default, SQL Server Express installs to a named instance.

The first (Transact-SQL) code listing creates a stored procedure used by this sample.

Compile the second (C++) code listing with odbc32.lib. Then, execute the program.

The third (Transact-SQL) code listing deletes the stored procedure used by this sample.

use AdventureWorks
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'TestParm')
   DROP PROCEDURE TestParm
GO

CREATE PROCEDURE TestParm 
@OutParm int OUTPUT 
AS
SELECT Name FROM Purchasing.Vendor
SELECT @OutParm = 88
RETURN 99
go
// compile with: odbc32.lib
#include <stdio.h>
#include <string.h>
#include <windows.h>
#include <sql.h>
#include <sqlext.h>
#include <odbcss.h>

#define MAXBUFLEN 255

SQLHENV henv = SQL_NULL_HENV;
SQLHDBC hdbc1 = SQL_NULL_HDBC;     
SQLHSTMT hstmt1 = SQL_NULL_HSTMT;

void Cleanup() {
   if (hstmt1 != SQL_NULL_HSTMT)
      SQLFreeHandle(SQL_HANDLE_STMT, hstmt1);

   if (hdbc1 != SQL_NULL_HDBC) {
      SQLDisconnect(hdbc1);
      SQLFreeHandle(SQL_HANDLE_DBC, hdbc1);
   }

   if (henv != SQL_NULL_HENV)
      SQLFreeHandle(SQL_HANDLE_ENV, henv);
}

int main() {
   RETCODE retcode;
   // SQLBindParameter variables.
   SWORD sParm1 = 0, sParm2 = 1;
   SQLLEN cbParm1 = SQL_NTS;
   SQLLEN cbParm2 = SQL_NTS;

   // Allocate the ODBC environment and save handle.
   retcode = SQLAllocHandle (SQL_HANDLE_ENV, NULL, &henv);
   if ( (retcode != SQL_SUCCESS_WITH_INFO) && (retcode != SQL_SUCCESS)) {
      printf("SQLAllocHandle(Env) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Notify ODBC that this is an ODBC 3.0 app.
   retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER) SQL_OV_ODBC3, SQL_IS_INTEGER);
   if ( (retcode != SQL_SUCCESS_WITH_INFO) && (retcode != SQL_SUCCESS)) {
      printf("SQLSetEnvAttr(ODBC version) Failed\n\n");
      Cleanup();
      return(9);    
   }

   // Allocate ODBC connection handle and connect.
   retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc1);
   if ( (retcode != SQL_SUCCESS_WITH_INFO) && (retcode != SQL_SUCCESS)) {
      printf("SQLAllocHandle(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   // This sample use Integrated Security. Create the SQL Server DSN by using the Windows NT authentication. 
   retcode = SQLConnect(hdbc1, (UCHAR*)"AdventureWorks", SQL_NTS, (UCHAR*)"",SQL_NTS, (UCHAR*)"", SQL_NTS);

   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
      printf("SQLConnect() Failed\n\n");
      Cleanup();
      return(9);
   }

   // Allocate statement handle.
   retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc1, &hstmt1);
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
      printf("SQLAllocHandle(hstmt1) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Bind the return code to variable sParm1.
   retcode = SQLBindParameter(hstmt1, 1, SQL_PARAM_OUTPUT, SQL_C_SSHORT, SQL_INTEGER, 0, 0, &sParm1, 0, &cbParm1);
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
      printf("SQLBindParameter(sParm1) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Bind the output parameter to variable sParm2.
   retcode = SQLBindParameter(hstmt1, 2, SQL_PARAM_OUTPUT, SQL_C_SSHORT, SQL_INTEGER, 0, 0, &sParm2, 0, &cbParm2);
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
      printf("SQLBindParameter(sParm2) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Execute the command. 
   retcode = SQLExecDirect(hstmt1, (UCHAR*)"{? = call TestParm(?)}", SQL_NTS);
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
      printf("SQLExecDirect Failed\n\n");
      Cleanup();
      return(9);
   }

   // Show parameters are not filled.
   printf("Before result sets cleared: RetCode = %d, OutParm = %d.\n", sParm1, sParm2);

   // Clear any result sets generated.
   while ( ( retcode = SQLMoreResults(hstmt1) ) != SQL_NO_DATA )
      ;

   // Show parameters are now filled.
   printf("After result sets drained: RetCode = %d, OutParm = %d.\n", sParm1, sParm2);

   // Clean up. 
   SQLFreeHandle(SQL_HANDLE_STMT, hstmt1);
   SQLDisconnect(hdbc1);
   SQLFreeHandle(SQL_HANDLE_DBC, hdbc1);
   SQLFreeHandle(SQL_HANDLE_ENV, henv);
}
use AdventureWorks
DROP PROCEDURE TestParm
GO
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