In MySQL, the CASE statement evaluates multiple conditions line by line.
If a condition is true, it returns the corresponding result.
If none of the conditions match, it returns a default value using the ELSE clause.
It is widely used in SELECT, UPDATE, DELETE, and ORDER queries efficiently.
The EXISTS operator is used to check if a subquery returns any rows.
When you write a query in SQL, you can use the EXISTS keyword with a subquery to determine whether the subquery returns one or more rows.
If it does, EXISTS evaluates to TRUE; if it returns no rows, EXISTS evaluates to FALSE.
