查詢花費很長時間執行

我有以下查詢，我正在使用這兩個運算符來獲取具有特定數字之間的年齡的記錄，但查詢花了很多時間來顯示結果，其鴨舌超過5分鐘仍運行查詢花費很長時間執行

SELECT 
    *, 
    (SELECT COUNT(*) 
    FROM users 
    WHERE 
    1=1 OR 
    LOWER(age) BETWEEN 18 AND 20 OR 
    LOWER(age) BETWEEN 20 AND 25 OR 
    LOWER(age) BETWEEN 25 AND 30 OR 
    LOWER(age) BETWEEN 30 AND 35 
) AS totalcount 
FROM users, states, countries, user_types, media 
WHERE 
    users.id_user_type = user_types.id AND 
    users.id_state = states.id AND 
    users.id_country = countries.id AND 
    media.id_user = users.id AND 
    media.profile_photo = 1 AND 
    users.id_user_type = 3 OR 
    LOWER(age) BETWEEN 18 AND 20 OR 
    LOWER(age) BETWEEN 20 AND 25 OR 
    LOWER(age) BETWEEN 25 AND 30 OR 
    LOWER(age) BETWEEN 30 AND 35 
ORDER BY users.id

令人不安的部分是：使用or條款你有（它沒有意義）

LOWER(age) BETWEEN 18 AND 20 OR 
LOWER(age) BETWEEN 20 AND 25 OR 
LOWER(age) BETWEEN 25 AND 30 OR 
LOWER(age) BETWEEN 30 AND 35

來源

2014-11-02 voyeger

你是什麼試圖用這個查詢來檢索？ – 2014-11-02 12:57:24

你怎麼得出這樣的結論：查詢的那一部分是令人不安的部分？ – Guffa 2014-11-02 12:57:29

避免。你的查詢可能做了很多CROSS JOIN操作，這就是爲什麼它需要很長時間（你的結果集很大）。

select *, 
     (
      select count(*) 
       from users 
      where 1=1 
       or lower(age) between 18 and 20 
       or lower(age) between 20 and 25 
       or lower(age) between 25 and 30 
       or lower(age) between 30 and 35 
     ) as totalcount 
    from users, states, countries, user_types, media 
    where users.id_user_type = user_types.id 
    and users.id_state = states.id 
    and users.id_country = countries.id 
    and media.id_user = users.id 
    and media.profile_photo = 1 
    and users.id_user_type = 3 
    order by users.id

此外，目前還不清楚你試圖用這個查詢來完成什麼。

回答這些問題可以幫助我們來幫您：

有什麼age列類型
你到底是從內部查詢

來源

2014-11-02 12:59:17

WHERE 1 = 1'和所有其他'BETWEEN'語句怎麼樣？爲什麼使用LOWER年齡），年齡是一個字符串嗎？爲什麼要把它和數字比較呢？我認爲你應該解決這些問題，當它說「它沒有意義」時。 – wolfgangwalther 2014-11-02 13:02:21

你or語句解析不正確期待什麼。您需要括號：

FROM users, states, countries, user_types, media 
WHERE (users.id_user_type = user_types.id AND 
     users.id_state = states.id AND 
     users.id_country = countries.id AND 
     media.id_user = users.id AND 
     media.profile_photo = 1 AND 
     (users.id_user_type = 3 OR 
     LOWER(age) BETWEEN 18 AND 20 OR 
     LOWER(age) BETWEEN 20 AND 25 OR 
     LOWER(age) BETWEEN 25 AND 30 OR 
     LOWER(age) BETWEEN 30 AND 35 
     )

書面，查詢所要做的五個表中一個完整的笛卡爾乘積，然後做一些怪異的過濾。

如果您使用適當的join語法，這基本上是一個非問題。簡單的規則：切勿在from子句中使用逗號。

另外，查詢似乎沒有意義。爲什麼要將age作爲字符串存儲（如使用lower()建議的那樣？那麼，爲什麼要將這些與整數進行比較？爲什麼要將連續範圍分成四個不同的比較，而不是僅僅說age between 18 and 35？

來源

2014-11-02 13:41:47

查詢花費很長時間執行

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