OTL 4.0, Example 78 (Simple Insert/Select/Update, MyODBC 2.50)

Example 78 (Simple Insert/Select/Update, MyODBC 2.50)

This example demonstrates simple INSERT, SELECT, UPDATE and constant SQL statements. This example works with MySQL via MyODBC. Pay attention to the restrictions [imposed by MyODBC] on the use of the OTL classes.

Source Code

#include <iostream>
using namespace std;

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define OTL_ODBC_MYSQL // Compile OTL 4.0/ODBC/MySQL
// #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 insert()
// insert rows into table
{ 
 otl_stream o(1, // buffer size should be == 1 always on INSERT
              "insert into test_tab values(:f1<int>,:f2<char[31]>)", 
                 // SQL statement
              db // connect object
             );
 char tmp[32];

 for(int i=1;i<=100;++i){
  sprintf(tmp,"Name%d",i);
  o<<i<<tmp;
 }
}

void update(const int af1)
// insert rows into table
{ 
 otl_stream o(1, // buffer size should be == 1 always on UPDATE
              "UPDATE test_tab "
              "   SET f2=:f2<char[31]> "
              " WHERE f1=:f1<int>", 
                 // UPDATE statement
              db // connect object
             );

 o<<"Name changed"<<af1;
 o<<otl_null()<<af1+1; // set f2 to NULL

}

void select(const int af1)
{ 
 // MyODBC does not allow any input bind variables in the WHERE clause
 // in a SELECT statement.
 // Therefore, the SELECT statement has to be generated literally.
 char stmbuf[1024];
 sprintf(stmbuf,
         "select * from test_tab where f1>=%d and f1<=%d*2",
         af1,
         af1
        );
 otl_stream i(50, // buffer size may be > 1
              stmbuf, // SELECT statement
              db // connect object
             ); 
   // create select stream
 
 int f1;
 char f2[31];

 while(!i.eof()){ // while not end-of-data
  i>>f1;
  cout<<"f1="<<f1<<", f2=";
  i>>f2;
  if(i.is_null())
   cout<<"NULL";
  else
   cout<<f2;
  cout<<endl;
 }

}

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

  db.rlogon("UID=scott;PWD=tiger;DSN=mysql"); // connect to ODBC
//  db.rlogon("scott/tiger@mysql"); // 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

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

  insert(); // insert records into the table
  update(10); // update records in the table
  select(8); // select records from the 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.sqlstate<<endl; // print out SQLSTATE message
  cerr<<p.var_info<<endl; // print out the variable that caused the error
 }

 db.logoff(); // disconnect from ODBC

 return 0;

}

Output

f1=8, f2=Name8
f1=9, f2=Name9
f1=10, f2=Name changed
f1=11, f2=NULL
f1=12, f2=Name12
f1=13, f2=Name13
f1=14, f2=Name14
f1=15, f2=Name15
f1=16, f2=Name16

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