# OTL 4.0, Example 217 (otl_stream::cancel() and DB2-CLI)

# Example 217 (otl_stream::cancel() and DB2-CLI)

This example demonstrates how to use otl_stream::cancel() in OTL/ODBC, OTL/DB2-CLI. The example works in Windows, VC++, only. With small modifications, the example can be ported to Unix, pthreads.

## Source Code

    #include <iostream>
    using namespace std;

    #include <stdio.h>
    #include <windows.h>
    #include <process.h>

    #define OTL_DB2_CLI // Compile OTL 4.0/DB2-CLI
    #include <otlv4.h> // include the OTL 4.0 header file

    otl_connect db; // connect object

    void insert()
    // insert rows into table
    {
     otl_stream o(50, // buffer size
                  "insert into test_tab values(:f1<float>,:f2<char[31]>)",
                     // SQL statement
                  db // connect object
                 );
     char tmp[32];

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

    otl_stream s;

    void select(void* dummy_par)
    {
     try{

      cout<<"Selecting..."<<endl;

      s.open(1, // buffer size
             "select count(*) "
             "from test_tab a1, test_tab a2, test_tab a3, "
             "     test_tab a4, test_tab a5 "
             "where 1=:f1<int>",
               // SELECT statement
             db // connect object
            );
       // Create select stream.
       // The ":f1" dummy input parameter is needed to give the stream
       // a chance to initialize its internal variables with the SELECT statement
       // BEFORE the SELECT statement starts executing

      int count;

      s<<1; // Now, forcing the execution of the SQL

      while(!s.eof()){ // while not end-of-data
       s>>count;
       cout<<"count="<<count<<endl;
      }
     }catch(otl_exception& p){
      cerr<<"Select() ===> "<<p.msg<<endl; // print out error message
      cerr<<"Select() ===> "<<p.stm_text<<endl; // print out SQL that caused the error
      cerr<<"Select() ===> "<<p.var_info<<endl; // print out the vari }
     }
     _endthread();
    }

    void cancel(void* dummy_par)
    {
     try{
       cout<<"Cancelling the SQL"<<endl;
       s.cancel();
     }catch(otl_exception& p){
       cout<<"Cancel() ===> "<<p.msg<<endl; // print out error message
       cout<<"Cancel() ===> "<<p.stm_text<<endl; // print out SQL that caused the error
       cout<<"Cancel() ===> "<<p.var_info<<endl; // print out the vari }
     }
     cout<<"End of Cancelling"<<endl;
     _endthread();

    }

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

      db.rlogon("scott/tiger@db2sql"); // connect to the database

      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 table
      _beginthread(select,0,NULL);
      Sleep(2000);
      _beginthread(cancel,0,NULL);
      Sleep(10000);
      cout<<"End of program"<<endl;
     }

     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 the database

     return 0;

    }

## Output

    Selecting...
    Cancelling the SQL
    End of Cancelling
    Select() ===>
    Select() ===> select count(*) from test_tab a1, test_tab a2, test_tab a3,      t
    est_tab a4, test_tab a5 where 1=?
    Select() ===>
    End of program

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Copyright © 1996, 2007, Sergei Kuchin, email: skuchin@ispwest.com, skuchin@gmail.com
.

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