MySQL: Check if there Exist Row(s) Matching a Condition

Question

I have been doing this for quite some time:

SELECT COUNT(*) FROM Table WHERE Condition = *Condition*;

Since I am not interested in the total number of rows returned, I wonder if there is a more efficient way to check if there exist any row(s) that match the condition without letting MySQL scan through the entire table.

Answer 1

SELECT CASE
         WHEN EXISTS(SELECT *
                     FROM   YourTable
                     WHERE  Condition = '*Condition*') THEN 1
         ELSE 0
       END  

Answer 2

Try

SELECT COUNT(*) FROM SmallTable
WHERE EXISTS(SELECT * FROM Table WHERE Condition = *Condition*)