title: mysql: which the better one use DAY() or WEEK()?
body: <p>I have a web task for counting some data inside DB. I must count this data daily, weekly, and monthly. </p>
  
  <p>For weekly, I am still confused to decide which MySQL syntax I should use for this case.
  There are two suggestions to resolve this problem: using <code>DAY()</code> or <code>WEEK()</code>.</p>
  
  <p>I want this syntax is not limited by a confusing thing. As should declare the first of the month and end of month or start in Sunday or Monday, etc. I want it every time cans for use (but focuses at weekly).</p>
  
  <p>Which is the one that I can use? DAY() or WEEK()?  </p>