/**********************************************************************
* FILENAME :    CallSPMultipleResultSets.c
*
*
* DESCRIPTION :
*               Simple ODBC example to use a stored procedure that has
*               two consecutive select statements which retrieve data
*               from two tables.
*
*               Illustrates the most basic call, in the form :
*
*               {CALL Stored_Procedure ()}
*
* ODBC USAGE :
*               Drops and recreates a procedure 'Multi_Result_Sets'
*               Confirms the procedure exists via SQLProcedures ()
*               Executes the procedure using SQLExecDirect()
*               For each result set:
*                   calls SQLNumResultCols() to establish no of
*                   columns in result set
*                   Loops using SQLFetch() until SQL_NO_DATA returned
*                   to obtain result set rows
*                   Calls SQLMoreResults() for next result set, if exists
*               Two results sets are retrieved, one for each table.
*/
#include <stdio.h>
#include <stdlib.h>
#include <sql.h>
#include <sqlext.h>
#include <string.h>

#include "util.c"
#include "CallSPUtil.c"

int main () {

    SQLHENV  henv  = SQL_NULL_HENV;   	// Environment
    SQLHDBC  hdbc  = SQL_NULL_HDBC;   	// Connection handle
    SQLHSTMT hstmt = SQL_NULL_HSTMT;  	// Statement handle
    SQLRETURN retcode;			// Return status

    SQLCHAR * strCallSP   = "{CALL Multi_Result_Sets()}";
    char    * strProcName = "Multi_Result_Sets";

    SQLSMALLINT columns; 		// Number of columns in result-set
    int i;

    // Allocate an environment handle
    retcode=SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
    CHECK_ERROR(retcode, "SQLAllocHandle(ENV)", henv, SQL_HANDLE_ENV);

    // Set ODBC Version
    retcode=SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION,
                          (void *) SQL_OV_ODBC3, 0);
    CHECK_ERROR(retcode, "SQLSetEnvAttr(SQL_ATTR_ODBC_VERSION)",
                henv, SQL_HANDLE_ENV);

    // Allocate a connection handle
    retcode=SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
    CHECK_ERROR(retcode, "SQLAllocHandle(SQL_HANDLE_DBC)",
                hdbc, SQL_HANDLE_DBC);

    // DSN
    retcode=SQLDriverConnect(hdbc, NULL, "DSN=DATASOURCE;", SQL_NTS, NULL, 0,
                             NULL, SQL_DRIVER_COMPLETE);
    CHECK_ERROR(retcode, "SQLDriverConnect(DATASOURCE)",
                hdbc, SQL_HANDLE_DBC);

    retcode = DropProcedure (hdbc, strProcName);
    retcode = CreateProcedure (hdbc, strProcName);
    retcode = ListProcedure (hdbc, strProcName);

    // Allocate a statement handle
    retcode=SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
    CHECK_ERROR(retcode, "SQLAllocHandle(SQL_HANDLE_STMT)",
                hstmt, SQL_HANDLE_STMT);

    retcode = SQLPrepare (hstmt, strCallSP, SQL_NTS);
    CHECK_ERROR(retcode, "SQLPrepare(SQL_HANDLE_STMT)",
                hstmt, SQL_HANDLE_STMT);

    retcode = SQLExecute (hstmt);
    CHECK_ERROR(retcode, "SQLExecute(SQL_HANDLE_STMT)",
                hstmt, SQL_HANDLE_STMT);

    printf ("\nPersonID   Firstname     Surname    "
            "Address       City");
    printf ("\n--------   ---------     -------    "
            "-------       ----\n");

    SQLLEN  indicator, RowCount;
    char *buf=malloc (255);

    do {
        // SQLNumResultCols() returns number of columns in result set.
        // If non zero use SQLFetch until SQL_NO_DATA returned
        retcode=SQLNumResultCols(hstmt, &columns);
       	CHECK_ERROR(retcode, "SQLNumResultCols()",
                    hstmt, SQL_HANDLE_STMT);
        printf ("\nColumns : %i", columns);
        if (columns > 0) {
            printf ("\nStart Fetch ...");
            while (SQLFetch(hstmt) != SQL_NO_DATA) {
        	// Loop through the columns
        	memset (buf, ' ', 255);
                printf ("\n");
        	for (i = 1; i <= columns; i++) {
        	    // retrieve column data as a string
        	    retcode = SQLGetData(hstmt, i, SQL_C_CHAR,
                                         buf, 255, &indicator);
        	    if (SQL_SUCCEEDED(retcode)) {
        	        // Handle null columns
        	        if (indicator == SQL_NULL_DATA)
                            strcpy (buf, "NULL");
        		    buf=rtrim(buf, ' ');
        		    if (i==1)
                            printf("%-8s ", buf);
                        else
                            printf("%-12s ", buf);
        	    }
        	}
            }
            printf ("\nEnd Fetch ...");
        } else {
            // SQLRowCount returns number of rows affected by
            // INSERT, UPDATE, DELETE or (if the driver provides) the
            // number of rows returned by a SELECT
            retcode=SQLRowCount(hstmt, &RowCount);
            CHECK_ERROR(retcode, "SQLRowCount()", hstmt, SQL_HANDLE_STMT);
            printf ("\nRow count is : %i\n", (int) RowCount);
        }
    } while (SQLMoreResults(hstmt) == SQL_SUCCESS);

exit:

    free (buf);

    printf ("\nComplete.\n");

    // Free handles
    // Statement
    if (hstmt != SQL_NULL_HSTMT)
        SQLFreeHandle(SQL_HANDLE_STMT, hstmt);

    // Connection
    if (hdbc != SQL_NULL_HDBC) {
        SQLDisconnect(hdbc);
        SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
    }

    // Environment
    if (henv != SQL_NULL_HENV)
        SQLFreeHandle(SQL_HANDLE_ENV, henv);

    return 0;
}

See Also


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