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Process ODBC Errors (ODBC)

Two ODBC function calls can be used to retrieve ODBC messages: SQLGetDiagRec and SQLGetDiagField. To obtain primary ODBC-related information in the SQLState, pfNative, and ErrorMessage diagnostic fields, call SQLGetDiagRec until it returns SQL_NO_DATA. For each diagnostic record, SQLGetDiagField can be called to retrieve individual fields. All driver-specific fields must be retrieved using SQLGetDiagField.

SQLGetDiagRec and SQLGetDiagField are processed by ODBC Driver Manager, not an individual driver. ODBC Driver Manager does not cache driver-specific diagnostic fields until a successful connection has been made. Calling SQLGetDiagField for driver-specific diagnostic fields is not possible before a successful connection. This includes the ODBC connection commands, even if they return SQL_SUCCESS_WITH_INFO. Driver-specific diagnostic fields will not be available until the next ODBC function call.

Description

This sample shows a simple error handler that calls SQLGetDiagRec for the standard ODBC information. It then tests for a valid connection, and if one exists, it calls SQLGetDiagField for the SQL Server ODBC driver-specific diagnostic fields. This sample is not supported on IA64.

This sample was developed for ODBC version 3.0 or later.

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.

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.

Execute the first (Transact-SQL) code listing to create the stored procedure used by this sample.

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

Execute the third (Transact-SQL) code listing to delete the stored procedure used by this sample.

Code

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

Go

CREATE PROCEDURE BadOne 
AS 
SELECT * FROM Purchasing.Vendor
Go

Code

// compile with: odbc32.lib
#include <stdio.h>
#include <string.h>
#include <windows.h>
#include <sql.h>
#include <sqlext.h>
#include <odbcss.h>

#define MAXBUFLEN 256

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

void ProcessLogMessages(SQLSMALLINT plm_handle_type, SQLHANDLE plm_handle, char *logstring, int ConnInd);

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;

   // 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. Please 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) ) {
         ProcessLogMessages(SQL_HANDLE_DBC, hdbc1, "SQLConnect() Failed\n\n", FALSE);
         Cleanup();
         return(9);
   }
   else {
      ProcessLogMessages(SQL_HANDLE_DBC, hdbc1,
         "\nConnect Successful\n\n", FALSE);
   }

   // Allocate statement handle, and then execute command.
   retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc1, &hstmt1);
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
      ProcessLogMessages(SQL_HANDLE_DBC, hdbc1, "SQLAllocHandle(hstmt1) Failed\n\n", TRUE);
      Cleanup();
      return(9);
   }

   retcode = SQLExecDirect(hstmt1, (UCHAR*)"exec BadOne", SQL_NTS);
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
         ProcessLogMessages(SQL_HANDLE_STMT, hstmt1, "SQLExecute() Failed\n\n", TRUE);
         Cleanup();
         return(9);
   }

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

   // Clean up. 
   SQLFreeHandle(SQL_HANDLE_STMT, hstmt1);
   SQLDisconnect(hdbc1);
   SQLFreeHandle(SQL_HANDLE_DBC, hdbc1);
   SQLFreeHandle(SQL_HANDLE_ENV, henv);
}

void ProcessLogMessages(SQLSMALLINT plm_handle_type, SQLHANDLE plm_handle, char *logstring, int ConnInd) {
   RETCODE plm_retcode = SQL_SUCCESS;
   UCHAR plm_szSqlState[MAXBUFLEN] = "", plm_szErrorMsg[MAXBUFLEN] = "";
   SDWORD plm_pfNativeError = 0L;
   SWORD plm_pcbErrorMsg = 0;
   SQLSMALLINT plm_cRecNmbr = 1;
   SDWORD plm_SS_MsgState = 0, plm_SS_Severity = 0;
   SQLINTEGER plm_Rownumber = 0;
   USHORT plm_SS_Line;
   SQLSMALLINT plm_cbSS_Procname, plm_cbSS_Srvname;
   SQLCHAR plm_SS_Procname[MAXNAME], plm_SS_Srvname[MAXNAME];

   if (logstring)
      printf(logstring);

   while (plm_retcode != SQL_NO_DATA_FOUND) {
      plm_retcode = SQLGetDiagRec(plm_handle_type, plm_handle, plm_cRecNmbr, 
                                  plm_szSqlState, &plm_pfNativeError, plm_szErrorMsg, 
                                  MAXBUFLEN - 1, &plm_pcbErrorMsg);

      // Note that if the application has not yet made a successful connection, 
      // the SQLGetDiagField information has not yet been cached by ODBC Driver Manager and 
      // these calls to SQLGetDiagField will fail.
      if (plm_retcode != SQL_NO_DATA_FOUND) {
         if (ConnInd) { 
            plm_retcode = SQLGetDiagField( plm_handle_type, plm_handle, plm_cRecNmbr,
                                                        SQL_DIAG_ROW_NUMBER, &plm_Rownumber,
                                                        SQL_IS_INTEGER, NULL);

            plm_retcode = SQLGetDiagField( plm_handle_type, plm_handle, plm_cRecNmbr,
                                           SQL_DIAG_SS_LINE, &plm_SS_Line, SQL_IS_INTEGER, NULL);

            plm_retcode = SQLGetDiagField( plm_handle_type, plm_handle, plm_cRecNmbr, 
                                           SQL_DIAG_SS_MSGSTATE, &plm_SS_MsgState,
                                           SQL_IS_INTEGER, NULL);

            plm_retcode = SQLGetDiagField( plm_handle_type, plm_handle, plm_cRecNmbr,
                                           SQL_DIAG_SS_SEVERITY, &plm_SS_Severity,
                                           SQL_IS_INTEGER, NULL);

            plm_retcode = SQLGetDiagField( plm_handle_type, plm_handle, plm_cRecNmbr,
                                           SQL_DIAG_SS_PROCNAME, &plm_SS_Procname,
                                           sizeof(plm_SS_Procname), &plm_cbSS_Procname);

            plm_retcode = SQLGetDiagField( plm_handle_type, plm_handle, plm_cRecNmbr,
                                           SQL_DIAG_SS_SRVNAME, &plm_SS_Srvname, 
                                           sizeof(plm_SS_Srvname), &plm_cbSS_Srvname);
         }

         printf("szSqlState = %s\n", plm_szSqlState);
         printf("pfNativeError = %d\n", plm_pfNativeError);
         printf("szErrorMsg = %s\n", plm_szErrorMsg);
         printf("pcbErrorMsg = %d\n\n", plm_pcbErrorMsg);

         if (ConnInd) {
            printf("ODBCRowNumber = %d\n", plm_Rownumber);
            printf("SSrvrLine = %d\n", plm_Rownumber);
            printf("SSrvrMsgState = %d\n", plm_SS_MsgState);
            printf("SSrvrSeverity = %d\n", plm_SS_Severity);
            printf("SSrvrProcname = %s\n", plm_SS_Procname);
            printf("SSrvrSrvname = %s\n\n", plm_SS_Srvname);
         }
      }

      plm_cRecNmbr++;   // Increment to next diagnostic record.
   }
}

Code

use AdventureWorks
DROP PROCEDURE BadOne
GO
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