Sql server 选择计数多表sql server返回1值

我的多重计数有问题

这是我的桌子

table1
ID UserId Username
1    a      aa
2    b      bb
3    c      cc
4    d      dd

table2
ID UserId2  note  
1   1       n1
2   1       n2
3   2       n3
4   2       n4 

table3
ID UserId3  testname
1    1      test1
2    1       test2
3    2       test3
4    2       test4
5    3       test 5

table4 

ID UserId  filename
1   1        filea
2   1        fileb
3   2        filec
4   2        filed

我有这样的疑问

    select ID, userID, username, 
    (select count(distinct table2.ID) from table2 where table2.userID2 = ID group by userID,username) as note_count , 
    (select count(distinct table3.ID) from table3 where table3.userID3 = ID group by userID,username) as PO_count,
select filename from table4 where table3.userID = table1.ID group by filename) as FileCount   
    from table1 ORDER BY userID

表3中的select count运行良好，但对于count table2，每行只返回1个值。我需要表4中按文件名列出的filecount组，怎么做？子查询出错。

请尝试以下操作：

SELECT
    t1.*,
    note_count = ISNULL(DISTINCT COUNT(t2.ID), 0),
    PO_count = ISNULL(DISTINCT COUNT(t3.ID), 0)
FROM table1 t1
LEFT JOIN table2 t2
    ON t2.UserId2 = t1.ID
LEFT JOIN table3 t3
    ON t3.UserId3 = t1.ID
GROUP BY
    t1.ID, t1.UserId, t1.Username
ORDER BY t1.UserId

或者您可以使用交叉应用：

---

这里有一些问题：-

在两个子查询中，实际上不需要GROUPBY语句。 子查询的WHERE子句中的ID应具有别名，以便它们正确链接到表1。 乙二醇

按照惯例，保持表和列名的大小写一致是一个好主意。如果要在SQL Server的区分大小写安装上安装查询，则不会编译此查询。

---

我不明白你为什么要使用countDISTINCT ID。这应该是你的密钥，而且每个记录都不同。这会让你需要这个

SELECT
    u.ID,
    u.UserName,
    (SELECT COUNT(*)
        FROM table2
        WHERE UserId2 = u.Id) AS note_count,
    (SELECT COUNT(*)
        FROM table3
        WHERE UserId3 = u.Id) AS test_count,
    (SELECT COUNT(*)
        FROM table4
        WHERE UserId4 = u.Id) AS file_count
FROM
    table1 u

另一方面，例如，如果用户1可以多次使用test1，但您只需要testname的不同计数，那么您可以将test\u count查询更改为

(SELECT COUNT(DISTINCT testname)
    FROM table3
    WHERE UserId3 = u.Id) AS test_count,

文件和便笺也一样

请尝试以下操作

SELECT
    ID,
    userID,
    username, 
    (SELECT COUNT(t2.ID)    FROM table2 t2 WHERE t2.userID2 = t1.ID) AS note_count, 
    (SELECT COUNT(t3.ID)    FROM table3 t3 WHERE t3.userID3 = t1.ID) AS PO_count,
    LTRIM(ISNULL(STUFF((SELECT 
                            ', ' + filename + ' (' + CAST(COUNT(filename) AS VARCHAR) + ')'
                        FROM
                            table4 t4
                        WHERE
                            t4.userID = t1.ID
                        GROUP BY
                            filename
                        FOR XML PATH('')
                        )
                        , 1, 1,''),'-'))
                AS FileCount
FROM
    table1 t1
ORDER BY
    t1.UserId

---

我认为子查询中不需要GROUP BY，我建议您使用限定ID。这适用于两个子查询，但例如：从table3中选择countdistinct table3.ID，其中table3.userID3=table1.ID作为PO_countthis nice，但我需要从table4中选择countfilename GROUP BY filename，我需要按文件名对组进行计数求和。请尝试更新的查询。检查它是否有用。如果您不想这样做，您需要在外部查询中使用JOIN with Filecount查询。但将显示重复的用户详细信息行。

(SELECT COUNT(DISTINCT testname)
    FROM table3
    WHERE UserId3 = u.Id) AS test_count,

SELECT
    ID,
    userID,
    username, 
    (SELECT COUNT(t2.ID)    FROM table2 t2 WHERE t2.userID2 = t1.ID) AS note_count, 
    (SELECT COUNT(t3.ID)    FROM table3 t3 WHERE t3.userID3 = t1.ID) AS PO_count,
    LTRIM(ISNULL(STUFF((SELECT 
                            ', ' + filename + ' (' + CAST(COUNT(filename) AS VARCHAR) + ')'
                        FROM
                            table4 t4
                        WHERE
                            t4.userID = t1.ID
                        GROUP BY
                            filename
                        FOR XML PATH('')
                        )
                        , 1, 1,''),'-'))
                AS FileCount
FROM
    table1 t1
ORDER BY
    t1.UserId