title: PHP - Insert variables in double quote strings
body: <p>I'm new here. I started PHP recently and I am wondering how I could insert variables, and put them into single quotes, into a double quotes string.
  Here's what I tried : 
  <code>$query = "INSERT INTO Table (Name, Activity) VALUES ('$name', '$activity');";</code>
  But when I check <code>$query</code>, it contains that : <code>INSERT INTO Table (Name, Activity) VALUES (,);</code>. I don't understand why it does that because when, instead of writing the above code, I write this one : <code>$query = "INSERT INTO Table (Name, Activity) VALUES ($name, $activity);";</code> (without the single quotes), the string contains this : <code>INSERT INTO Table (Name, Activity) VALUES (Robert, Book-seller);</code>. Does anybody have a clue ?</p>