Question

我使用ASP.NET Membership，最重要的是我添加了一些与用户有一对多关系的表。

一个用户有很多钢笔，笔记本等。

我正在编写自定义成员资格提供程序并修改了select查询以检索有关用户的所有信息以及用户拥有的笔数和“工具”总数，但查询显然会执行灾难性的操作。无论如何得到那些信息？这就是我的尝试：

SET STATISTICS TIME ON
SELECT  m.Email, m.PasswordQuestion, m.IsApproved, m.CreateDate, m.LastLoginDate,
        u.LastActivityDate, m.LastPasswordChangedDate, u.UserId, m.IsLockedOut, 
        m.LastLockoutDate, CAST(m.Comment as nvarchar(max)) as Comment, 
        COUNT(DISTINCT cl.Id) AS NumberOfPens, 
        COUNT(DISTINCT cf.Id)+
             COUNT(DISTINCT cm.Id) +
             COUNT(DISTINCT ce.Id) +
             COUNT(DISTINCT cl.Id) +
             COUNT(DISTINCT cp.Id) +
             COUNT(DISTINCT csl.Id)+
             COUNT(DISTINCT cs.Id) +
             COUNT(DISTINCT cshl.Id) AS NumberOfTools
FROM  aspnet_Membership AS m 
      INNER JOIN aspnet_Users AS u ON m.UserId = u.UserId 
      INNER JOIN Pens AS cf ON u.UserId = cf.Owner 
      INNER JOIN Notebooks AS cm ON u.UserId = cm.Owner 
      INNER JOIN Rulers AS ce ON u.UserId = ce.Owner 
      INNER JOIN Calculators AS cl ON u.UserId = cl.Owner 
      CROSS JOIN aspnet_Applications AS a
GROUP BY u.UserId, m.Email, m.PasswordQuestion, m.IsApproved, 
         m.CreateDate, m.LastLoginDate, u.LastActivityDate, 
         m.LastPasswordChangedDate, m.IsLockedOut, m.LastLockoutDate, 
         CAST(m.Comment as nvarchar(max))

SET STATISTICS TIME OFF

91位用户

9分11秒！

Answer 1

SELECT  m.Email, m.PasswordQuestion, m.IsApproved, m.CreateDate, m.LastLoginDate,
        u.LastActivityDate, m.LastPasswordChangedDate, u.UserId, m.IsLockedOut, 
        m.LastLockoutDate, CAST(m.Comment as nvarchar(max)) as Comment,
        penCount,
        notebookCount + rulerCount + calculatorCount AS toolCount
FROM    aspnet_Membership m
JOIN    aspnet_Users u
ON      u.userId = m.userId
CROSS APPLY
        (
        SELECT  COUNT(*)
        FROM    pens
        WHERE   owner = u.UserId
        ) p (penCount)
CROSS APPLY
        (
        SELECT  COUNT(*)
        FROM    notebooks
        WHERE   owner = u.UserId
        ) n (notebookCount)
CROSS APPLY
        (
        SELECT  COUNT(*)
        FROM    rulers
        WHERE   owner = u.UserId
        ) r (rulerCount)
CROSS APPLY
        (
        SELECT  COUNT(*)
        FROM    calculators
        WHERE   owner = u.UserId
        ) c (calculatorCount)

Answer 2

快速点击，最后取出cross join - 您没有使用它，只是将结果倍增并减慢速度。

此外，您可以在加入之前执行计数，这将保存group by并允许RDBMS并行化查询，如下所示：

SELECT     
    m.Email, 
    m.PasswordQuestion, 
    m.IsApproved, 
    m.CreateDate, 
    m.LastLoginDate, 
    u.LastActivityDate, 
    m.LastPasswordChangedDate, 
    u.UserId, 
    m.IsLockedOut, 
    m.LastLockoutDate, 
    CAST(m.Comment as nvarchar(max)) as Comment, 
    PenCount AS NumberOfPens, 
    PenCount + NotebookCount + RulerCount + CalculatorCount AS NumberOfTools
FROM
    aspnet_Membership AS m 
    INNER JOIN aspnet_Users AS u ON 
        m.UserId = u.UserId 
    INNER JOIN (select owner, count(1) as PenCount from Pens group by owner) AS cf ON 
        u.UserId = cf.Owner 
    INNER JOIN (select owner, count(1) as NotebookCount from Notebooks group by owner) AS cm ON 
        u.UserId = cm.Owner 
    INNER JOIN (select owner, count(1) as RulerCount from Rulers group by owner) AS ce ON 
        u.UserId = ce.Owner 
    INNER JOIN (select owner, count(1) as CalculatorCount from Calculators group by owner) AS cl ON 
        u.UserId = cl.Owner

请注意，如果用户可能没有所有工具，则您需要LEFT加入以代替inner加入，然后将所有{{}包裹起来{1}} *Count列。

使用count优化SQL查询

2 个答案: