SQL在一个查询中有多个选择计数语句

我有没有关系的数据。只需要计算3个表格中的各列，并将它们作为视图显示在页面上。SQL在一个查询中有多个选择计数语句

这是到目前为止的代码，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

什么是什么数据库您使用的是你和错误？ –

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

应该这样做。

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2012-06-28 11:30:14

这工作！谢谢。我试图接受答案，但它告诉我等5分钟。生病后就做吧！ – user999690

@ user999690您不必快速接受答案。当一个问题还没有得到答案时，它动机人们回答它。那么你可以有多个解决方案来解决你的问题:-) –

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

假设你有喜欢这里的表（有一个名为xxx场tableXxx表），查询由具有逗号有语法错误AS C,后，没有那个逗号，它工作正常（至少使用SQLite，因为MSSQL是不是在sqlfiddle对我来说）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

顺便说一句，你可以简化您的查询

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

由于我已经减少了2页的加载时间超过200％，另一个减少了30％ – user3455363

这个怎么样？

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

继吕克M的回应，它提供了一个单一的列表，与具有单独值的列。你可以想象这是多么有用可能是...

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在一个查询中有多个选择计数语句

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