SQL在一個查詢中有多個選擇計數語句

我有沒有關係的數據。只需要計算3個表格中的各列，並將它們作爲視圖顯示在頁面上。SQL在一個查詢中有多個選擇計數語句

這是到目前爲止的代碼，但不工作：

SELECT COUNT(cars) AS A, 
     (SELECT COUNT(boats) FROM tableBoats) AS B, 
     (SELECT COUNT(trees) FROM tableTrees) AS C, 
FROM tableCars

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2012-06-28 user999690

什麼是什麼數據庫您使用的是你和錯誤？ –

SELECT A, B, C 
FROM (SELECT COUNT(cars) as A FROM tableCars) a 
CROSS JOIN (SELECT COUNT(boats) as B FROM tableBoats) b 
CROSS JOIN (SELECT COUNT(trees) as C FROM tableTrees) c

應該這樣做。

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2012-06-28 11:30:14

這工作！謝謝。我試圖接受答案，但它告訴我等5分鐘。生病後就做吧！ – user999690

@ user999690您不必快速接受答案。當一個問題還沒有得到答案時，它動機人們回答它。那麼你可以有多個解決方案來解決你的問題:-) –

SELECT * 
FROM 
(
    SELECT 'Nb cars' as description, COUNT(cars) AS count_item FROM tableCars 
    UNION ALL 
    SELECT 'Nb boats' as description, COUNT(boats) AS count_item FROM tableBoats 
    UNION ALL 
    SELECT 'Nb tress' as description, COUNT(trees) AS count_item FROM tableTrees 
) temp

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2012-06-28 11:36:27

假設你有喜歡這裏的表（有一個名爲xxx場tableXxx表），查詢由具有逗號有語法錯誤AS C,後，沒有那個逗號，它工作正常（至少使用SQLite，因爲MSSQL是不是在sqlfiddle對我來說）工作：

http://sqlfiddle.com/#!5/5fa6c/3

SELECT COUNT(cars) AS A, 
     (SELECT COUNT(boats) FROM tableBoats) AS B, 
     (SELECT COUNT(trees) FROM tableTrees) AS C 
FROM tableCars

順便說一句，你可以簡化您的查詢

SELECT (SELECT COUNT(cars) FROM tableCars) AS A, 
     (SELECT COUNT(boats) FROM tableBoats) AS B, 
     (SELECT COUNT(trees) FROM tableTrees) AS C

其他的答案也完美:)

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2012-06-28 11:52:44 biziclop

由於我已經減少了2頁的加載時間超過200％，另一個減少了30％ – user3455363

這個怎麼樣？

SELECT 
    (SELECT COUNT(*) FROM tableCars) car_count, 
    (SELECT COUNT(*) FROM tableBoats) boat_count, 
    (SELECT COUNT(*) FROM tableTrees) tree_count

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2012-06-28 11:57:28

繼呂克M的迴應，它提供了一個單一的列表，與具有單獨值的列。你可以想象這是多麼有用可能是...

SELECT C.Accountnum as AccountNum, C.Address as Address, 'C' as Source 
From CustTable C 
Where C.AccountNum like '000%' 
Union All 
Select V.Accountnum as AccountNum, V.Name as Address, 'V' as Source 
from VendTable V 
Where V.AccountNum like 'A%'

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2013-09-09 14:15:19 mprouty

SQL在一個查詢中有多個選擇計數語句

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