title: Informix - Date/Time Manipulation in where clause
body: <p>See below query:</p>
  
  <pre><code>DROP TABLE IF EXISTS rd_rt_date_integer;
  CREATE TABLE rd_rt_date_integer
  (
      run_date    DATE NOT NULL,
      run_time    INTEGER NOT NULL
                  CHECK (run_time &gt;= 0 AND run_time &lt; 2400 AND MOD(run_time, 100) &lt; 60),
      PRIMARY KEY(run_date, run_time)
  );
  
  INSERT INTO rd_rt_date_integer VALUES('2017-05-22', 0);
  INSERT INTO rd_rt_date_integer VALUES('2017-05-22', 100);
  INSERT INTO rd_rt_date_integer VALUES('2017-05-22', 200);
  INSERT INTO rd_rt_date_integer VALUES('2017-05-22', 300);
  INSERT INTO rd_rt_date_integer VALUES('2017-05-22', 400);
  
  SELECT run_date, run_time,
         EXTEND(run_date, YEAR TO MINUTE) +
         MOD(run_time, 100) UNITS MINUTE +
         (run_time / 100) UNITS HOUR AS run_date_time
    FROM rd_rt_date_integer;
  </code></pre>
  
  <p>Question: How can we apply condition in where to clause to fetch data from certain time onwards</p>
  
  <pre><code>SELECT run_date, run_time,
         EXTEND(run_date, YEAR TO MINUTE) +
         MOD(run_time, 100) UNITS MINUTE +
         (run_time / 100) UNITS HOUR AS run_date_time
    FROM rd_rt_date_integer
  where EXTEND(run_date, YEAR TO MINUTE) +
         MOD(run_time, 100) UNITS MINUTE +
         (run_time / 100) UNITS HOUR &gt;='2017-05-22 02:00'
  </code></pre>
  
  <p>I just want to understand what is the best way to do manipulation in where clause itself where im concatenating run_date and run_time...</p>