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Bulk Copy a SELECT Result Set (ODBC)

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This sample shows how to use bulk copy functions to bulk copy out the result set of a SELECT statement. 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.

To bulk copy out the result set of a SELECT statement

  1. Allocate an environment handle and a connection handle.

  2. Set SQL_COPT_SS_BCP and SQL_BCP_ON to enable bulk copy operations.

  3. Connect to SQL Server.

  4. Call bcp_init to set the following information:

    • Specify NULL for the szTable parameter.

    • The name of the data file that receives result set data.

    • The name of a data file to receive any bulk copy error messages (specify NULL if you do not want a message file).

    • The direction of the copy: DB_OUT.

  5. Call bcp_control, set eOption to BCPHINTS and place in iValue a pointer to a SQLTCHAR array containing the SELECT statement.

  6. Call bcp_exec to execute the bulk copy operation.

When using these steps the file is created in native format. You can convert the data values to other data types by using bcp_colfmt. For more information, see Create a Bulk Copy Format File (ODBC).

Example

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.

Compile with odbc32.lib and odbcbcp.lib.

// compile with: odbc32.lib odbcbcp.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;
HDBC hdbc1 = SQL_NULL_HDBC;

void Cleanup() {
   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;

   // Bulk copy variables.
   SDWORD cRows;
   SQLTCHAR szBCPQuery[] = "SELECT BirthDate FROM HumanResources.Employee";

   // 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, set bulk copy mode, and then 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);
   }

   retcode = SQLSetConnectAttr(hdbc1, SQL_COPT_SS_BCP, (void *)SQL_BCP_ON, SQL_IS_INTEGER);
   if ( (retcode != SQL_SUCCESS_WITH_INFO) && (retcode != SQL_SUCCESS)) {
      printf("SQLSetConnectAttr(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Sample use Integrated Security, create SQL Server DSN using 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);
   }

   // Initialize the bulk copy.
   retcode = bcp_init(hdbc1, NULL, "BCPODBC.bcp", "BCPERROR.out", DB_OUT);
   // The test is for the bulk copy return of SUCCEED, not the ODBC return of SQL_SUCCESS.
   if ( (retcode != SUCCEED) ) {
      printf("bcp_init(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Specify the query to use.
   retcode = bcp_control(hdbc1, BCPHINTS, (void *)szBCPQuery);
   if ( (retcode != SUCCEED) ) {
      printf("bcp_control(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Execute the bulk copy.
   retcode = bcp_exec(hdbc1, &cRows);
   if ( (retcode != SUCCEED) ) {
      printf("bcp_exec(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   printf("Number of rows bulk copied out = %d.\n", cRows);

   // Cleanup
   SQLDisconnect(hdbc1);
   SQLFreeHandle(SQL_HANDLE_DBC, hdbc1);
   SQLFreeHandle(SQL_HANDLE_ENV, henv);
}

See Also

Other Resources

Bulk Copying with the SQL Server ODBC Driver How-to Topics (ODBC)