title: How to create index in firebird for improvement of select query
body: <p>I am newbie in using firebird. I have 3 tables. </p>
  
  <p>for <strong>T_TABLE1</strong> the structure is shown below:</p>
  
  <p><img src="https://i.stack.imgur.com/nKsKx.png" alt="enter image description here"></p>
  
  <p>for <strong>T_TABLE2</strong> the structure is shown below:</p>
  
  <p><img src="https://i.stack.imgur.com/nVRDV.png" alt="enter image description here"></p>
  
  <p>and for <strong>T_TABLE3</strong> the structure is like this:</p>
  
  <p><img src="https://i.stack.imgur.com/TPLNi.jpg" alt="enter image description here"></p>
  
  <p>the primary key is the <strong>ID</strong> from <strong>T_TABLE1</strong> to <strong>TBL1_ID</strong> in <strong>T_TABEL2</strong> and <strong>TBL1_ID</strong> in <strong>T_TABLE3</strong>. How can I select data join with that 3 tables and I want to use <strong>index</strong> for best select query but I don't know how to create index because I am newbie in using firebird and I want to learn more in using firebird. Hope my explanation is clear.</p>