title: abstracting data-type heterogeneity of different database
body: <p>In my current  project, I have a requirement of abstracting data-type heterogeneity among different database.</p>
  
  <p>For instance,  I have a table in MySQL database. Table name is <code>FIRSTTABLE(badgeID *Integer* , pref INT)</code>.</p>
  
  <p>I have a table in Apache-Derby database. Table name is <code>FIRSTTABLE (badgeID *varchar(12)*, pref INT)</code>.</p>
  
  <p>Now,  query component, which queries MySQL database and Apache Derby database at same time, has badgeID as "double".</p>
  
  <p>My requirement is that query-component should not know underlying database (either MySQL or Apache Derby). Its query should be independent of type of database.</p>
  
  <p>How could I resolve this issue ? My research problem is not limited to MySQL or Apach-Derby. For clarity, I have taken an example of Apache-Derby and MySQL.</p>