title: Database structure for storing timestamp in PHP
body: <p>I have a website, in that i start time after user login, and when i stop the timer I save this time in database, And i have two tables </p>
  
  <pre><code>login 
  ----------------------
  id | username | password 
  
  table 
  ---------------------------------------------
  user_id(referenced by id) | t_id | date | time
  </code></pre>
  
  <p>So, With this database structure i got multiple entry in database when i logout, 
  So plz tell me about proper database structure for storing the time datewise and for one date only one entry allowed.</p>
  
  <p>If there are any suggesion for re-design database structure then plz suggest me.</p>
  
  <p>i want to merge the time in database, when i logout the multiple time in single day...</p>