左連接 - 未知列錯誤1054

Question

我不斷收到＃1054 - 'where子句'中的未知列'color'。

我的查詢的簡化版本如下。

SELECT *, "red" AS colour 
FROM (
    SELECT *,'calls' AS 'tbl', id AS cid FROM calls) as c 
WHERE colour='red' 
ORDER BY colour ASC, c.created_date DESC 

如果我刪除WHERE行，查詢執行得很好，顏色被識別並且一切正常。

任何幫助，將不勝感激。

Answer 1

這是因爲你不能在你的WHERE和ORDER BY子句中使用別名

所以，你將不得不做一些像

SELECT *, IF(c.status = '1', "green", "red") AS colour 
FROM (
    SELECT *,'calls1' AS 'tbl', id AS cid FROM calls1 
    WHERE uid LIKE '%1111%' 
    ORDER BY timestamp DESC 
    UNION 
    SELECT *,'calls2' AS 'tbl', id AS cid FROM calls2 
    WHERE uid LIKE '%1111%' 
    ORDER BY timestamp DESC 
) as c 
LEFT JOIN objects AS o ON o.call_id = c.id 
WHERE c.status = 'the color id you want' // or you can rewrite your if here 
ORDER BY c.status ASC, c.timestamp DESC 

或者，這爲您簡化查詢

SELECT *, "red" AS colour 
FROM (
    SELECT *,'calls' AS 'tbl', id AS cid FROM calls) as c 
WHERE c.status = 'the color id you want' 
ORDER BY c.created_date DESC 

爲什麼按顏色分類，如果它總是紅色？

Answer 2

試試這個WHERE c.status !='1'

SELECT *, IF(c.status = '1', "green", "red") AS colour 
FROM (
    SELECT *,'calls1' AS 'tbl', id AS cid FROM calls1 
    WHERE uid LIKE '%1111%' 
    ORDER BY timestamp DESC 
    UNION 
    SELECT *,'calls2' AS 'tbl', id AS cid FROM calls2 
    WHERE uid LIKE '%1111%' 
    ORDER BY timestamp DESC 
) as c 
LEFT JOIN objects AS o ON o.call_id = c.id 
WHERE c.status != '1' 
ORDER BY colour ASC, c.timestamp DESC 

Answer 3

爲您更新的問題，我認爲你可以做別名

SELECT * FROM (
SELECT *, "red" AS colour 
FROM (
    SELECT *,'calls' AS 'tbl', id AS cid FROM calls) as c 
) as v 
WHERE colour='red' 
ORDER BY colour ASC, v.created_date DESC 

Answer 4

使用在where子句是不是一個好方法一欄。請參考以下鏈接。

http://dev.mysql.com/doc/refman/5.0/en/problems-with-alias.html

---

標準SQL不允許在WHERE子句中的列別名引用。這種限制是強加的，因爲當WHERE子句被評估時，列值可能還沒有被確定。例如，下面的查詢是非法的：

SELECT id, COUNT(*) AS cnt FROM tbl_name WHERE cnt > 0 GROUP BY id; 

---

使用具有的別名或更改條件WHERE子句中使用精確的列名。