psqlODBC HOWTO - Ch

Author: Wayne Cheng (wayne@softintegration.com)
Release Date: 23 September 2003
Description: Example based Mini-Howto on Accessing PostgreSQL from Ch

Ch is a C/C++ interpreter from http://www.softintegration.com.
It is designed for cross-platform scripting, shell programming, 2D/3D plotting, numerical computing, and embedded scripting.

Requirements to get the code to work:

• Ch Standard Edition or Professional Edition
• Ch ODBC Toolkit.
• IODBC, UNIXODBC or Microsoft ODBC manager.
• A PostgreSQL datasource.

% ch
                                   Ch 
                  Standard edition, version 4.0.0.11291 
              (C) Copyright 2001-2003 SoftIntegration, Inc.
                     http://www.softintegration.com
/home/wcheng> cd $CHHOME/package/iodbc/demos
/usr/local/ch/package/iodbc/demos> ls
odbctest.c  simple.c
/usr/local/ch/package/iodbc/demos> ./simple.c
SQLAllocHandle() OK
SQLSetEnvAttr() ok
SQLAllocHandle() ok
SQLSetConnectAttr() ok
/usr/local/ch/package/iodbc/demos> cat simple.c

/**************************** 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);
     }
}