OTL 4.0, Example 32
(otl_stream::describe_select() with a simple Select)

Example 32 (otl_stream::describe_select() with a simple Select)

This example demonstrates the otl_stream::describe_select() with a simple SELECT statement.

Source Code

#include <iostream>
using namespace std;

#include <stdio.h>

#define OTL_ODBC // Compile OTL 4.0/ODBC
#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 where f1>=:f<int> and f1<=:f*2",
                 // 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=mssql"); // 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=2
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=-1
otl_var_dbtype=9
dbsize=2147483647
scale=0
prec=2147483647
nullok=1

Copyright &cop9; 1996-2018, Sergei Kuchin, email: skuchin@gmail.com, skuchin@gmail.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. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.