title: custom Auto increment in Mysql table
body: <p>I have three customer Id in my table, Let's Say A,B,C.I want to create order table for managing orders from these customers. I want to create orderID columns in such away that it must be auto increment with cunstomer Id appended eg. orderID column records : </p>
  
  <pre><code>A_1  ---&gt;A's 1st order,
  A_2  ---&gt;A's 2nd order,
  B_1  ---&gt;B's 1st order,
  C_1  ---&gt;C's 1st order,
  A_3  ---&gt;A's 3rd order,
  C_2  ---&gt;C's 2nd order,
  C_3  ---&gt;C's 3rd order,
  B_2  ---&gt;B's 2nd order,
  A_4  ---&gt;A's 4th order,
  A_5  ---&gt;A's 5th order
  </code></pre>