mysql存儲過程中的多個select語句

Question

我正在學習編寫存儲過程。我想有三個select語句到我的mysql存儲過程。 第二個和第三個select語句需要其上部select語句的結果。 我試着寫如下。但沒有成功。

CREATE DEFINER=`root`@`localhost` PROCEDURE `SPTeam`(IN date_x date, OUT emplist3 varchar(200)) 

BEGIN 
SELECT 
(
    select emp_event.employee_id as emplist1 
    from emp_event 
    where emp_event.date = date_x 
), 
(
    select emp_position.employee_id as emplist2 
    from emp_position 
    where FIND_IN_SET(emp_position.employee_id, emplist1)=0 
    AND emp_position.position = "Cameraman" 
), 
(
    select employee.name as emplist3 
    from employee 
    where employee.id IN (emplist2) 
); 
END 

這是我得到的錯誤。

Error Code: 1054. Unknown column 'emplist1' in 'where clause' 

有人請糾正我。 謝謝U.

Answer 1

你可以存儲每個變量的選擇結果，然後做一個選擇這些變量：

DECLARE @emp_event as int 
DECLARE @emp_position as int 
DECLARE @emp_employeeName as int 

SET @emp_event = (select emp_event.employee_id from emp_event where emp_event.date = date_x) 
SET @emp_position = (select emp_position.employee_id from emp_position where FIND_IN_SET(emp_position.employee_id, @emp_event)=0 AND emp_position.position = "Cameraman") 
SET @emp_employeeName = (select employee.name from employee where employee.id IN (@emp_position)) 

SELECT @emp_event as emplist1, @emp_position as emplist2, @emp_employeeName as emplist3 

Answer 2

如果我understeand正確，您需要什麼，這將是這樣的：

select employee.name as emplist3 
    from employee 
    where employee.id IN (
     select emp_position.employee_id 
     from emp_position 
     where emp_position.employee_id IN (
     select emp_event.employee_id 
     from emp_event 
     where emp_event.date = date_x 
    ) 
     AND emp_position.position = "Cameraman" 
    )