子查询使用我的sql返回1行以上

Question

我试图从一个MySQL数据库中创建一个select语句来选择id用户(雇员或领导或经理)和全名。根据id部门，id优先级。代码是:

PROCEDURE `get_parent`(id_dept int, id_priorty int )
BEGIN
if(select employee_tb.id_dept  from employee_tb where (employee_tb.id_dept=id_dept&&3=id_priorty))>0
then
begin
select id_employee ,full_name,3 as type from employee_tb;
end;
elseif(select leader_tb.id_dept from leader_tb where (leader_tb.id_dept=id_dept&&id_priorty=2))>0
 then
 begin
 select id_leader, full_name, 2 as type from leader_tb;
 end;
 elseif(select manager_tb.id_dept from manager_tb where (manager_tb.id_dept=id_dept&&id_priorty=1))>0
 then 
 begin
 select id_manager, full_name, 1 as type from manager_tb;
 end;
 else
 select "failed"as result ;
 end if;
END

Answer 1

select id_employee ,full_name,3 as type from employee_tb;

select id_leader, full_name, 2 as type from leader_tb;

select id_manager, full_name, 1 as type from manager_tb;

检查条件后代码中的这3行无论如何都会从表中选择所有记录。

要解决此问题：

PROCEDURE `get_parent`(id_dept int, id_priorty int )
BEGIN
if(select employee_tb.id_dept  from employee_tb where (employee_tb.id_dept=id_dept&&3=id_priorty))>0
then
begin
select id_employee ,full_name,3 as type from employee_tb where (employee_tb.id_dept=id_dept&&3=id_priorty);
end;
elseif(select leader_tb.id_dept from leader_tb where (leader_tb.id_dept=id_dept&&id_priorty=2))>0
 then
 begin
 select id_leader, full_name, 2 as type from leader_tb where (leader_tb.id_dept=id_dept&&id_priorty=2);
 end;
 elseif(select manager_tb.id_dept from manager_tb where (manager_tb.id_dept=id_dept&&id_priorty=1))>0
 then 
 begin
 select id_manager, full_name, 1 as type from manager_tb where (manager_tb.id_dept=id_dept&&id_priorty=1);
 end;
 else
 select "failed"as result ;
 end if;
END

如果有一条记录匹配这个where子句，它当然会给出一条记录。