在 MySQL 中选择查询

Question

两张桌子

表1

ID FileName

1  abc
2  abc
3  abc
4  xyz

表2

ID Table1_ID isDeleted
1   1        1
2   2        1
3   3        0
4   4        0

我需要通过传递 table1 的任何 ID 来获取 isDeleted=1 的文件名计数，即对于 ID 的所有值 (1,2,3)，我需要计数为 2

我尝试了以下查询

SELECT COUNT(t1.FileName) FROM Table1 t1 
LEFT OUTER JOIN Table1 t11 ON t1.FileName=t11.FileName 
INNER JOIN table2 t2 ON t2.Table1_ID =t1.ID AND t2.isDeleted=1
WHERE t1.ID=X; 

X-1,2,3

这总是返回 3。

编辑：我需要通过从第一个表中传递 ID 来从第一个表中获取文件名的计数。计数应基于第二个表中的 isdeleted 列。这些表通过列 ID (table1) 和 Table1_ID (table2) 关联

Answer 1

试一试：

select SUM(isDeleted)
from Table2 
where Table1_ID in (
  select ID from Table1
  where FileName = (select FileName
                    from Table1
                    where ID = 1)
)

编辑：获取文件数：

select count(*) 
from Table1 a
join Table2 b on a.ID = b.Table1_ID and b.isDeleted = 1
where a.FileName = (select FileName
                   from Table1
                   where ID = 1)

Answer 2

这对我有用：

declare @id int
set @id = 1 /*Or 2 or 3 or 4, etc.*/

select sum(isdeleted)
from table2
where table1_id in 
    (select id 
    from table1 
    where filename = (select filename 
                      from table1 
                      where id = @id))

编辑：我看不出这与 Fosco 的回答有何不同。

Answer 3

SELECT COUNT(t1.FileName) FROM Table1 t1 
INNER JOIN table2 t2 ON t2.Table1_ID =t1.ID AND t2.isDeleted=1
WHERE t1.ID=X;