MS Access在查询中使用多个子查询

Question

我有问题。

我想获得3个表的COUNT个，其中一个名称类似于'La'，所以我创建了此查询：

SELECT COUNT(a.ID), COUNT(b.ID), COUNT(c.ID)
FROM (SELECT * FROM Artists WHERE Artistname LIKE "La*")  a, (SELECT * FROM Albums WHERE Name LIKE "La*")  b, (SELECT * FROM Songs WHERE Name LIKE "La*")  c

这返回我3乘以0，但是当我只运行一个子查询时，我得到以下结果：

SELECT * FROM Artists WHERE Artistname LIKE "La*"

返回1 ...

我在做什么错？

Answer 1

将表达式放入SELECT：

SELECT COUNT(*) as artist_cnt,
       (SELECT COUNT(*) FROM Albums WHERE Name LIKE "La*") as album_cnt,
       (SELECT COUNT(*) FROM Songs WHERE Name LIKE "La*") as song_cnt
FROM (SELECT COUNT(*) as artist_cnt
      FROM Artists
      WHERE Artistname LIKE "La*"
     ) as a;

嗯，除了第一个COUNT()以外的所有。 MS Access在FROM子句中需要某些内容，因此将它们全部移到SELECT上比较棘手。

Answer 2

返回这三列：

Answer 3

如果在子查询中执行计数，则每个子查询将完全返回一个记录