MYSQL - 不能創建視圖

Question

SELECT branches.brid, 
COALESCE(a.cnt, 0) AS Assigned, 
COALESCE(c.cnt, 0) AS Completed, 
COALESCE(p.cnt, 0) AS Pending, 
COALESCE(x.cnt, 0) AS Expired 
FROM branches WHERE access = 'User' 
LEFT JOIN 
(SELECT brid, count(*) from task GROUP BY brid) a ON branches.brid = a.brid 
LEFT JOIN 
(SELECT brid, count(*) from task WHERE stat = 'Completed' GROUP BY brid) c ON branches.brid = c.brid 
LEFT JOIN 
(SELECT brid, count(*) from task WHERE stat = 'Pending' GROUP BY brid) p ON branches.brid = p.brid 
LEFT JOIN 
(SELECT brid, count(*) from task WHERE stat = 'Expired' GROUP BY brid) x ON branches.brid = x.brid 
ORDER BY branches.brid ASC; 

我得到這個錯誤，當我創建視圖有沒有辦法做到這一點？此查詢工作，但我不能在我的數據庫中創建視圖

ERROR 1349（HY000）：視圖的SELECT包含在FROM子句中

Answer 1

子查詢的錯誤或多或少解釋本身。

這裏是從documentation的摘錄，你需要運行MySQL 5.7.7或更新的版本能在一個視圖中使用子查詢。

視圖定義是受到以下限制：

的MySQL 5.7.7之前，SELECT語句不能包含在一個子查詢 FROM子句。 ....

你或許可以重寫查詢以這樣的事：

SELECT branches.brid, 
COUNT(t.stat) AS Assigned, 
SUM(CASE WHEN t.stat = 'Completed' THEN 1 ELSE 0 END) AS Completed, 
SUM(CASE WHEN t.stat = 'Pending' THEN 1 ELSE 0 END) AS Pending, 
SUM(CASE WHEN t.stat = 'Expired' THEN 1 ELSE 0 END) AS Expired 
FROM branches 
LEFT JOIN task t ON branches.brid = t.brid 
WHERE access = 'User' 
GROUP BY branches.brid 
ORDER BY branches.brid ASC;