OTL 4.0, Example 84
(otl_stream::describe_select() with a simple Select)

Example 84 (otl_stream::describe_select() with a simple Select)

This example demonstrates the otl_stream::describe_select() with a simple SELECT statement in MyODBC/MySQL.

Source Code

#include <iostream.h>
#include <stdio.h>
#define OTL_ODBC_MYSQL // Compile OTL 4.0/MyODBC
// #define OTL_ODBC_UNIX // uncomment this line if UnixODBC is used
#include <otlv4.h> // include the OTL 4.0 header file

otl_connect db; // connect object

void select()
{ 
 otl_stream i(1, // buffer size
              "select * from test_tab",
                 // SELECT statement
              db // connect object
             ); 
   // create select stream
 
 otl_column_desc* desc;
 int desc_len;

 desc=i.describe_select(desc_len);

 for(int n=0;n<desc_len;++n){
  cout<<"========== COLUMN #"<<n+1<<" ==========="<<endl;
  cout<<"name="<<desc[n].name<<endl;
  cout<<"dbtype="<<desc[n].dbtype<<endl;
  cout<<"otl_var_dbtype="<<desc[n].otl_var_dbtype<<endl;
  cout<<"dbsize="<<desc[n].dbsize<<endl;
  cout<<"scale="<<desc[n].scale<<endl;
  cout<<"prec="<<desc[n].prec<<endl;
  cout<<"nullok="<<desc[n].nullok<<endl;
 }
 

}

int main()
{
 otl_connect::otl_initialize(); // initialize ODBC environment
 try{

  db.rlogon("uid=scott;pwd=tiger;dsn=mysql"); // connect to ODBC

  otl_cursor::direct_exec
   (
    db,
    "drop table test_tab",
    otl_exception::disabled // disable OTL exceptions
   ); // drop table

  otl_cursor::direct_exec
   (
    db,
    "create table test_tab(f1 int, f2 varchar(30), f3 text)"
    );  // create table

  select(); // select records from table

 }

 catch(otl_exception& p){ // intercept OTL exceptions
  cerr<<p.msg<<endl; // print out error message
  cerr<<p.stm_text<<endl; // print out SQL that caused the error
  cerr<<p.var_info<<endl; // print out the variable that caused the error
 }

 db.logoff(); // disconnect from ODBC

 return 0;

}

Output

========== COLUMN #1 ===========
name=f1
dbtype=4
otl_var_dbtype=4
dbsize=0
scale=0
prec=0
nullok=1
========== COLUMN #2 ===========
name=f2
dbtype=12
otl_var_dbtype=1
dbsize=0
scale=0
prec=0
nullok=1
========== COLUMN #3 ===========
name=f3
dbtype=-1
otl_var_dbtype=9
dbsize=0
scale=0
prec=0
nullok=1

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Copyright © 1996, 2001, Sergei Kuchin, email: skuchin@sprynet.com, kuchin@hotmail.com .

Permission to use, copy, modify and redistribute this document for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies.

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