Question

我的SQL非常生疏，我想确保我不会在任何类型的负载下编写失败的东西。

我有一个Message表，如下所示：

ID int [PK]
ThreadId nvarchar(32)
Read bit
Archived bit
Timestamp datetime
/*---Other non-relevant columns---*/
Sender_MemberId int [FK]
Receiver_MemberId int [FK]

与Gmail类似，我希望能够根据正常的消息使用情况（收件箱，已发送，存档等）提取该线程的所有线程和所有消息。

这是我目前用于收件箱的SQL：

SELECT * FROM [Messages]
WHERE [ThreadId] IN 
(
    SELECT [ThreadId]
    FROM [Messages]
    WHERE ([Receiver_MemberId] = @MemberId)
)
ORDER BY [ThreadId] DESC, [Timestamp] DESC

这可以按我的意愿运作，但是有更好的方法吗？或者如果没有，我应该拥有什么索引？

更新：根据Aaron的好建议，我已经添加了分页功能，并减少了我正在接下来的信息量。

新SQL：

SELECT DISTINCT m.[ThreadId], m.[Subject], m.[To], m.[From], m.[Timestamp]
FROM 
(   
    SELECT ROW_NUMBER() OVER (ORDER BY MessageId) AS RowNumber , ThreadId
    FROM [Messages]
    WHERE [Sender_MemberId] = @p1
) 
AS t
INNER JOIN [Messages] m ON m.ThreadId = t.ThreadId
WHERE t.RowNumber BETWEEN @Skip + 1 AND @Skip + @Take
ORDER BY [Timestamp] DESC

Answer 1

您不需要子查询，这应该

  SELECT Id
       , [ThreadId]
       , read
       , archived
       , timestamp
  FROM   [Messages]
  WHERE  [Receiver_MemberId] = @MemberId
  ORDER BY [ThreadId] DESC, [Timestamp] DESC

最好为您需要的列命名，而不是使用*

更好的SQL来拉线程和消息？

1 个答案: