In this lesson we look at the previous challenge and dissect it. "DELETE FROM celebs WHERE twitter_handle IS NULL;" We see that the DELETE FROM clause which allows us to delets rows from a table. This is followed with the name of the table we want to delete. A where clause lets us select which rows we want to delete. "IS NULL" is the SQL condition that will return true if the value is NULL and false otherwise. We end this lesson with a new concept, constraints, which we will go over in the next lesson.