SQL:Count（*）和groupby具有不同的表

我有两张表，如下所示

第一表TBL类别

第二表tblWord

所需输出

在产出方面

TotalCount是来自tblWord的按类别ID分组的计数*

播放的是count*，其中isPlayed=1组，按类别ID从tblword开始

所以为了从2表中得到结果，我尝试了以下错误的查询

select (select count(*) from tblwords group by categoryid) as count, (select count(*) from tblwords where isPlayed = 1 group by categoryid) as played, categoryID, categoryname from tblcategory

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查询中是否有获得所需输出或任何有用链接的建议？

以获得总计数的准确输出

SELECT t.categoryID, t.name,
       COUNT(*) as TotalCount, SUM(isplayed) as Played
FROM tblCategory t
INNER JOIN tblWord tw
ON t.categoryID = tw.categoryID
GROUP BY t.categoryID, t.name

要获取仅显示为1的计数

SELECT t.categoryID, t.name,
       COUNT(*) as TotalCount, SUM(isplayed) as Played
FROM tblCategory t
INNER JOIN tblWord tw
ON t.categoryID = tw.categoryID
WHERE isPlayed=1
GROUP BY t.categoryID, t.name

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以获得具有总计数的精确输出

SELECT t.categoryID, t.name,
       COUNT(*) as TotalCount, SUM(isplayed) as Played
FROM tblCategory t
INNER JOIN tblWord tw
ON t.categoryID = tw.categoryID
GROUP BY t.categoryID, t.name

要获取仅显示为1的计数

SELECT t.categoryID, t.name,
       COUNT(*) as TotalCount, SUM(isplayed) as Played
FROM tblCategory t
INNER JOIN tblWord tw
ON t.categoryID = tw.categoryID
WHERE isPlayed=1
GROUP BY t.categoryID, t.name

我先聚合，然后加入

我会先聚合，然后加入。

试试这个

SELECT tw.Category_ID, tc.NAME,
       COUNT(*) AS TotalCount, SUM(tw.IsPlayed=1) AS Played ,SUM(tw.IsPlayed=0) AS NonPlayed
FROM Table_Category  tc
INNER JOIN Table_Word tw 
ON tc.Category_ID = tw.Category_ID 
-- WHERE tw.IsPlayed=1
GROUP BY tc.Category_ID, tc.NAME

这里SUMtw.IsPlayed=1为播放状态，SUMtw.IsPlayed=0为非播放状态，因此您将同时获得播放和非播放状态

SELECT tw.Category_ID, tc.NAME,
       COUNT(*) AS TotalCount, SUM(tw.IsPlayed=1) AS Played ,SUM(tw.IsPlayed=0) AS NonPlayed
FROM Table_Category  tc
INNER JOIN Table_Word tw 
ON tc.Category_ID = tw.Category_ID 
-- WHERE tw.IsPlayed=1
GROUP BY tc.Category_ID, tc.NAME

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这里，SUMtw.IsPlayed=1作为播放，SUMtw.IsPlayed=0作为未播放，因此您将同时获得播放和未播放的记录

@milkey我们可以使用上述查询仅获得IsPlayed=1条记录吗？@Giri sumisPlayed表示IsPlayed=1条记录的计数。如果愿意，您也可以将其添加到内部select上的where子句中，但count和sum将为您提供相同的值。@milkey使用上述查询只能获得isPlayed=1条记录吗？@Giri sumisPlayed表示isPlayed=1条记录的计数。如果愿意，您也可以将其添加到内部select上的where子句中，但count和sum将为您提供相同的值。@m hasan使用上述查询是否只能获得isPlayed=1记录？@mhasan:isPlayed is bool。。。但我真的很惊讶我们能应用sum。得到了精确的输出。并且学到了新的东西sum:@m hasan使用上面的查询只能得到isPlayed=1条记录吗？@mhasan:isPlayed是bool。。。但我真的很惊讶我们能应用sum。得到了精确的输出。并学到了新东西sum：