SQL条件显示记录

Question

tbl_users

u_id | u_type | u_first_name 
1  U  I_am_user 
2  E  I_am_emp 
3  E  I_am_emp2 

tbl_order

o_id | u_id | e_id | o_status | pay_status 
    1  1  0 pending Unpaid 
    2  1  2 pick  Paid 
    3  1  0 pending Unpaid 
    4  1  3 Pick  paid 

我尝试此查询或者显示用户和EMP名

SELECT o.*, a.u_first_name as user, b.u_first_name as emp 
    FROM `tbl_order` AS o 
     LEFT JOIN tbl_users AS a ON a.u_id = o.u_id 
     LEFT JOIN tbl_users AS b ON b.u_id = o.e_id 

o_id | u_id | e_id | user | emp | pay_staus 

我们怎么将给条件（顺序其他1）先显示未付款（pay_status）记录 然后e_id=0记录然后全部休息？

Answer 1

从WHERE条款您的查询应该是这样的：

WHERE e_id = 0 OR pay_status = 'Unpaid' 
ORDER BY pay_status DESC; 

所以你的整个查询应该是这样的：

SELECT o.*, a.u_first_name as user, b.u_first_name as emp 
    FROM `tbl_order` AS o 
     LEFT JOIN tbl_users AS a ON a.u_id = o.u_id 
     LEFT JOIN tbl_users AS b ON b.u_id = o.e_id 
    WHERE e_id = 0 OR pay_status = 'Unpaid' 
    ORDER BY pay_status DESC; 

编辑：（From OP's comment）

如果要显示所有记录，但在特定的顺序，你只需要使用ORDER BY条款是这样的：

ORDER BY pay_status DESC, e_id ASC; 

Answer 2

试试这个：

select * from(
SELECT o.*, a.u_first_name as user, b.u_first_name as emp, 0 as rnk 
FROM `tbl_order` AS o 
LEFT JOIN tbl_users AS a ON a.u_id = o.u_id 
LEFT JOIN tbl_users AS b ON b.u_id = o.e_id 
where pay_status='Unpaid'  
union all 
SELECT o.*, a.u_first_name as user, b.u_first_name as emp, 1 as rnk 
FROM `tbl_order` AS o 
LEFT JOIN tbl_users AS a ON a.u_id = o.u_id 
LEFT JOIN tbl_users AS b ON b.u_id = o.e_id 
where pay_status!='Unpaid' and e_id=0 
union all 
SELECT o.*, a.u_first_name as user, b.u_first_name as emp, 2 as rnk 
FROM `tbl_order` AS o 
LEFT JOIN tbl_users AS a ON a.u_id = o.u_id 
LEFT JOIN tbl_users AS b ON b.u_id = o.e_id 
where pay_status!='Unpaid' and e_id!=0)a 
order by rnk