If you mean all columns whose email is unique: SELECT * FROM table WHERE email in (SELECT email FROM table GROUP BY email HAVING ... ... <看更多>

A brief beginner's introduction to the DISTINCT operator in SQL. DISTINCT creates a set of unique records ... ... <看更多>

You probably don't want to hear this, but the best option to speed up SELECT DISTINCT is to avoid DISTINCT to begin with. In many cases (not all!) it can be ... ... <看更多>