Question

我想将左联接转换为view table。

Following is my SQL

 SELECT d.account_no, COALESCE(d.deposits, 0) - COALESCE(w.withdrawals, 0) 
   AS balance
  FROM (SELECT account_no, SUM(deposit_amount) AS deposits
   FROM deposits
  GROUP BY account_no) d
  LEFT JOIN (SELECT account_no, SUM(withdraw_amount) AS withdrawals
       FROM withdraws
       GROUP BY account_no) w ON w.account_no = d.account_no

我想创建view表。

我该怎么做？有人可以帮忙吗？

Answer 1

创建视图（一次）并在左联接中使用

CREATE  VIEW my_view AS 
SELECT account_no, SUM(withdraw_amount) AS withdrawals
       FROM withdraws
       GROUP BY account_no
;


SELECT d.account_no, COALESCE(d.deposits, 0) - COALESCE(w.withdrawals, 0) 
 AS balance
FROM (SELECT account_no, SUM(deposit_amount) AS deposits
 FROM deposits
GROUP BY account_no) d
LEFT JOIN my_view  w ON w.account_no = d.account_no

加入查看表转换

1 个答案: