MYSQL：来自table1的SELECT 1，其中Id = 1 vs SELECT EXISTS（来自table1的SELECT 1，其中Id = 1）

Question

I want to check whether row exists or not in table1 , Here the condition is on Primary key so want to check which of the query is best to use and why?

QUERY 1: SELECT 1 from table1 where Id = 1;
QUERY 2: SELECT EXISTS(SELECT 1 from table1 where Id = 1)

NOTE: Id is primary key here.

Thanks!!

Answer 1

With my MySQL :

IF (SELECT EXISTS(SELECT 1 from table1 where Id = 1)) THEN
    -- ...
END ID;

Or without the IF

SELECT EXISTS(SELECT 1 from table1 where Id = 1) as 'Exists';

Will show

+--------+
| Exists |
+--------+
|      1 |
+--------+

OR

+--------+
| Exists |
+--------+
|      0 |
+--------+