# OTL 4.0, Example 154 (set_transaction_isolation_level, DB2-CLI)

# Example 154 (set_transaction_isolation_level, DB2-CLI)

This example demonstrates the use of otl_connect::set_transaction_isolation_level() for DB2-CLI.

## Source Code

    #include <iostream>
    using namespace std;

    #include <stdio.h>

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

    otl_connect db1, db2, db3; // connect objects

    void insert()
    // insert rows into table
    {
     otl_stream o(50, // buffer size
                  "insert into test_tab values(:f1<float>,:f2<char[31]>)",
                     // SQL statement
                  db1 // connect object
                 );
     o.set_commit(0); // set stream's auto-commit to OFF

     char tmp[32];

     for(int i=1;i<=100;++i){
      sprintf(tmp,"Name%d",i);
      o<<(float)i<<tmp;
     }
     o.set_flush();
     // At this point, rows are posted but not yet committed to the database
    }

    void select(otl_connect& db)
    {
     otl_stream i(50, // buffer size
                  "select * from test_tab where f1>=:f<int> and f1<=:ff<int>*2",
                     // SELECT statement
                  db // connect object
                 );
       // create select stream

     float f1;
     char f2[31];

     i<<4<<4; // assigning :f = 4, :ff = 4
       // SELECT automatically executes when all input variables are
       // assigned. First portion of output rows is fetched to the buffer

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

    }

    int main()
    {
     otl_connect::otl_initialize(); // initialize DB2-CLI environment
     try{

      db1.rlogon("UID=scott;PWD=tiger;DSN=db2sql"); // connect to DB2

      db2.rlogon("UID=scott;PWD=tiger;DSN=db2sql"); // connect to DB2
      db3.rlogon("UID=scott;PWD=tiger;DSN=db2sql"); // connect to DB2

      db2.set_transaction_isolation_level(otl_tran_read_uncommitted);
      db3.set_transaction_isolation_level(otl_tran_read_committed);

      otl_cursor::direct_exec
       (
        db1,
        "drop table test_tab",
        otl_exception::disabled // disable OTL exceptions
       ); // drop table

      otl_cursor::direct_exec
       (
        db1,
        "create table test_tab(f1 int, f2 varchar(30))"
        );  // create table

      db1.commit(); // committing the DDLs to the database

      insert(); // insert records into table

      cout<<"=======> Reading uncommitted data..."<<endl;
      select(db2); // select records from table

      db1.commit(); // committing the inserted rows to the database

      cout<<"=======> Reading committed data..."<<endl;
      select(db3); // 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.sqlstate<<endl; // print out SQLSTATE message
      cerr<<p.var_info<<endl; // print out the variable that caused the error
     }

     db1.logoff(); // disconnect from DB2
     db2.logoff(); // disconnect from DB2
     db3.logoff(); // disconnect from DB2

     return 0;

    }

## Output

    =======> Reading uncommitted data...
    f1=4, f2=Name4
    f1=5, f2=Name5
    f1=6, f2=Name6
    f1=7, f2=Name7
    f1=8, f2=Name8
    =======> Reading committed data...
    f1=4, f2=Name4
    f1=5, f2=Name5
    f1=6, f2=Name6
    f1=7, f2=Name7
    f1=8, f2=Name8

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