在MySQL中，我如何在子查詢中創建JOIN？

工作樣品

SELECT t.* FROM (
    SELECT 
    TITLE.name, 
    (TITLE.value-TITLE.msp) AS Lower, 
    (TITLE.value+TITLE.msp) AS Upper, 
    (TITLE.value) AS Value 
    FROM TITLE 
) t 
WHERE 98 BETWEEN t.Lower AND t.Upper 
ORDER BY ABS(98 - t.Value) ASC 
LIMIT 5

期望例如具有3個表（需要固定/幫助）

SELECT t.* FROM (
    SELECT 
    TITLE.name, ALBUM.year, GENRE.Type 
    (TITLE.value-TITLE.msp) AS Lower, 
    (TITLE.value+TITLE.msp) AS Upper, 
    (TITLE.value) AS Value 
    FROM TITLE, ALBUM, GENRE 
) t 
WHERE ALBUM.ID=GENRE.ID AND TITLE.ID=ALBUM.ID 
AND 98 BETWEEN t.Lower AND t.Upper 
ORDER BY ABS(98 - t.Value) ASC;

我得到以下錯誤工作：

ERROR 1054 (42S22): Unknown column 'ALBUM.ID' in 'where clause'

來源

2012-02-08 stackoverflow

您的子查詢（「t」）正在返回排除其各自ID值的TITLE，ALBUM和GENRE的交叉結果集。你的WHERE子句只能在't'的投影上操作。 – 2012-02-08 18:29:24

這是合乎邏輯的：你的子查詢創建一個表t，和後記嘗試引用表ALBUM。沒有ALBUM，只有t

最快的修復方法是移動它所屬的JOIN的WHERE子句：在子查詢中。

SELECT t.* FROM (
    SELECT 
    TITLE.name, ALBUM.year, GENRE.Type 
    (TITLE.value-TITLE.msp) AS Lower, 
    (TITLE.value+TITLE.msp) AS Upper, 
    (TITLE.value) AS Value 
    FROM TITLE, ALBUM, GENRE 
    WHERE ALBUM.ID=GENRE.ID AND TITLE.ID=ALBUM.ID 
) t 
WHERE 98 BETWEEN t.Lower AND t.Upper 
ORDER BY ABS(98 - t.Value) ASC;

查詢本身是不是漂亮，但...爲什麼不試試這個：

SELECT 
    TITLE.name, ALBUM.year, GENRE.Type 
    (TITLE.value-TITLE.msp) AS Lower, 
    (TITLE.value+TITLE.msp) AS Upper, 
    (TITLE.value) AS Value 
    FROM TITLE 
    JOIN ALBUM 
    ON TITLE.ID=ALBUM.ID 
    JOIN GENRE 
    ON ALBUM.ID=GENRE.ID 
    WHERE 98 BETWEEN Lower AND Upper 
    ORDER BY ABS(98 - Value) ASC;

刪除了不必要的子查詢
使用SQL-92式聯接，而不是SQL -89樣式JOIN（帶有where子句的笛卡爾積）

來源

2012-02-08 18:29:04 Konerak

有道理感謝Konerak＆rsenna – stackoverflow 2012-02-08 19:02:32

@Jammin我只是修正了他的「笛卡兒」的拼寫:) Konerak是唯一負責這個答案（我同意是最好的）。 – rsenna 2012-02-09 16:01:16

看看你的查詢：你正在定義一個名爲的子查詢，它在表TITLE,ALBUM和GENRE之間做cartesian product。 Then您從該子查詢中選擇，並嘗試應用TITLE,ALBUM和GENRE上的WHERE子句......但這些表已不在範圍內！

試試這個：

SELECT t.* FROM (
    SELECT 
    TITLE.name, ALBUM.year, GENRE.Type 
    (TITLE.value-TITLE.msp) AS Lower, 
    (TITLE.value+TITLE.msp) AS Upper, 
    (TITLE.value) AS Value 
    FROM TITLE, ALBUM, GENRE 
    WHERE ALBUM.ID=GENRE.ID AND TITLE.ID=ALBUM.ID 
) t 
WHERE 98 BETWEEN t.Lower AND t.Upper 
ORDER BY ABS(98 - t.Value) ASC;

來源

2012-02-08 18:29:01 rsenna

將WHERE子句移到內部查詢中。

SELECT t.* FROM (
    SELECT 
    TITLE.name, ALBUM.year, GENRE.Type 
    (TITLE.value-TITLE.msp) AS Lower, 
    (TITLE.value+TITLE.msp) AS Upper, 
    (TITLE.value) AS Value 
    FROM TITLE, ALBUM, GENRE 
    WHERE ALBUM.ID=GENRE.ID AND TITLE.ID=ALBUM.ID 
) t 
AND 98 BETWEEN t.Lower AND t.Upper 
ORDER BY ABS(98 - t.Value) ASC;

來源

2012-02-08 18:30:05

在MySQL中，我如何在子查詢中創建JOIN？

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