Ch ODBC Demos.

The program simple.c below illustrates how Ch ODBC is used. This program does not make a real connection to the database. You may need to configure your DSN and set up database tables for database operations such as update, query, and insert. Check the ODBC document for more information regarding programming in ODBC.

This simple.c program can be found in the directory CHHOME/toolkit/demos/ODBC/ after installation of the Ch ODBC toolkit, where CHHOME is the home directory in which Ch is installed. The program is readily to run without compilation, which will give you a quick start on programming ODBC in Ch.

/**************************** simple.c *****************************/ 
#include <sqlext.h>
#include <stdio.h>

void ODBC_error (       /* Get and print ODBC error messages */
    SQLHENV henv,       /* ODBC Environment */
    SQLHDBC hdbc,       /* ODBC Connection Handle */
    SQLHSTMT hstmt)     /* ODBC SQL Handle */
{
    UCHAR   sqlstate[10];
    UCHAR   errmsg[SQL_MAX_MESSAGE_LENGTH];
    SDWORD  nativeerr;
    SWORD   actualmsglen;
    RETCODE rc = SQL_SUCCESS;

    while ( rc != SQL_NO_DATA_FOUND)
    {
        rc = SQLError(henv, hdbc, hstmt,
             sqlstate, &nativeerr, errmsg,
             SQL_MAX_MESSAGE_LENGTH - 1, &actualmsglen);
  
        if (rc == SQL_ERROR) {
            printf ("SQLError failed!\n");
            return;
        }

       if (rc != SQL_NO_DATA_FOUND) {
           printf ("SQLSTATE = %s\n", sqlstate);
           printf ("NATIVE ERROR = %d\n", nativeerr);
           errmsg[actualmsglen] = '\0';
           printf ("MSG = %s\n\n", errmsg);
       }
     }

     if (hdbc != SQL_NULL_HDBC)
     {
           SQLFreeHandle (SQL_HANDLE_DBC, hdbc);
     }
     if (henv != SQL_NULL_HENV)
     {
           SQLFreeHandle (SQL_HANDLE_ENV, henv);
     }
}

int main(void)
{
    SQLHENV       henv    = SQL_NULL_HENV;
    SQLHDBC       hdbc    = SQL_NULL_HDBC;
    SQLHSTMT     hstmt   = SQL_NULL_HSTMT;
    RETCODE       rc      = SQL_SUCCESS;

    rc = SQLAllocHandle (SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);

    if (rc != SQL_ERROR)
    {
       printf("SQLAllocHandle() OK\n");
       rc = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3,0);
       if (rc != SQL_ERROR)
       {
          printf("SQLSetEnvAttr() ok\n");
          rc = SQLAllocHandle (SQL_HANDLE_DBC, henv, &hdbc);
          if ( rc != SQL_ERROR)
          {
             printf("SQLAllocHandle() ok\n");
             rc = SQLSetConnectAttr(hdbc, SQL_ATTR_AUTOCOMMIT, SQL_AUTOCOMMIT_OFF,0);
             if (rc != SQL_ERROR)
             {
               printf("SQLSetConnectAttr() ok\n");
               SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
               SQLFreeHandle(SQL_HANDLE_ENV, henv);
             }
           }
        }
    }

   if (rc == SQL_ERROR)
   {
      ODBC_error (henv, hdbc, hstmt);
   }
}