Example 145 (otl_stream::describe_select() with a simple Select)

Source Code

#include <iostream>
using namespace std;

#include <stdio.h>

// #define OTL_ODBC_UNIX // uncomment this line if UnixODBC is used
#define OTL_ODBC_ALTERNATE_RPC
#if !defined(_WIN32) && !defined(_WIN64)
#define OTL_ODBC
#else 
#define OTL_ODBC_POSTGRESQL // required with PG ODBC on Windows
#endif
#include <otlv4.h> // include the OTL 4.0 header file


otl_connect db; // connect object

void select()
{ 
 otl_stream i(10, // 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=postgresql"); // connect to ODBC
//  db.rlogon("scott/tiger@postgresql"); // connect to ODBC, alternative format
                                    // of connect string
  otl_cursor::direct_exec
   (
    db,
    "drop table test_tab",
    otl_exception::disabled // disable OTL exceptions
   ); // drop table

   db.commit();

  otl_cursor::direct_exec
   (
    db,
    "create table test_tab(f1 int, f2 varchar(30), f3 timestamp, f4 text)"
    );  // create table

  db.commit(); // committing the create table statement to to the database

  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=10
scale=0
prec=10
nullok=1
========== COLUMN #2 ===========
name=f2
dbtype=12
otl_var_dbtype=1
dbsize=30
scale=0
prec=30
nullok=1
========== COLUMN #3 ===========
name=f3
dbtype=93
otl_var_dbtype=8
dbsize=21
scale=0
prec=21
nullok=1
========== COLUMN #4 ===========
name=f4
dbtype=-1
otl_var_dbtype=9
dbsize=8190
scale=0
prec=8190
nullok=1

Copyright © 1996-2024, Sergei Kuchin, email: skuchin@gmail.com, skuchin@gmail.com .

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