Single row subquery

       In Single row subquery, inner query returns 'Zero or One' row. Based on the inner query result outer query will return output. The operators that can be used with single-row subqueires are =, >, >=, <, <=, and <>.

Example:

           Employee table

           Department table

SELECT * FROM EMPLOYEE

WHERE Dept_ID =

(

      SELECT

      DEPTID

      FROM DEPT

      WHERE DeptID = 10

)