子查询返回多行

Question

Suppose I had two tables, t_employee and t_leave .

I would like to print employeeName & substituteEmployeeName .

In the t_employee table, there is id of employee and name of the employee.

In the t_leave , there is id of t_leave, employee_id & substitute_id .

I have tried this code but it will not work.

SELECT *,
(SELECT t_employee.name FROM t_employee JOIN t_leave WHERE temployee.id=t_leave.substitute_id)
FROM t_leave JOIN t_employee
WHERE t_employee.id=t_leave.employee.id

Can someone help me? Thanks!

Answer 1

You have to LImit it to one, or use Aggregation function LIKE MAX or MIN

SELECT *,
(SELECT t_employee.name FROM t_employee JOIN t_leave WHERE temployee.id=t_leave.substitute_id ORDER BY t_employee.name LIMIT 1 )
FROM t_leave JOIN t_employee
WHERE t_employee.id=t_leave.employee.id