如何计算表中每行的行数？

Question

我从table1:

获取行

SELECT table1.id,  COUNT(commentTable1.id) AS CNT3,  COUNT(photoTable1.id) AS CNT2, COUNT(fileTable1.id)  AS CNT3 FROM table1 
LEFT JOIN commentTable1 ON...
LEFT JOIN photoTable1 ON...
LEFT JOIN fileTable1 ON ...

如何正确使用GROUP BY每个COUNT？现在我得错了CNT3

Answer 1

您无法按计数进行分组，因此我假设您按table1.id

进行分组

SELECT table1.id,  COUNT(commentTable1.id) AS CNT3,  COUNT(photoTable1.id) AS CNT2, COUNT(fileTable1.id)  AS CNT3 FROM table1 
LEFT JOIN commentTable1 ON...
LEFT JOIN photoTable1 ON...
LEFT JOIN fileTable1 ON ...
GROUP BY table1.id