Question

我在sql server中的注释表结构为

CREATE TABLE [dbo].[LS_Commentes](
    [CommentId] [int] IDENTITY(1,1) NOT NULL,
    [OwnerId] [uniqueidentifier] NULL,
    [OwnerName] [nvarchar](50) NULL,
    [Email] [nvarchar](250) NULL,
    [Date] [nvarchar](15) NULL,
    [ParentId] [int] NULL,
    [CommentText] [nvarchar](400) NULL,
    [ItemId] [int] NULL,
    [upVotes] [int] NULL,
    [downVotes] [int] NULL,
    [isApproved] [bit] NULL,
 CONSTRAINT [PK_LS_MsgCommentes] PRIMARY KEY CLUSTERED 
(
    [CommentId] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

我有这样的样本数据：

CommentId   OwnerId OwnerName   Email   Date    ParentId    CommentText ItemId  upVotes downVotes   isApproved
1   NULL    Test Commneter  NULL    1/4/2013    NULL    test    9   0   0   NULL
2   NULL    Test Commneter  NULL    1/4/2013    1   test    NULL    0   0   NULL
3   NULL    Test Commneter  NULL    1/4/2013    1   test    NULL    0   0   NULL

我想写一个查询可以让我所有的行都有itemid = 9而行有parentid =选择的注释ID（因为itemid = 9）

看这里我可以通过在子评论中添加项目ID 9来解决它，但我只是想知道是否可以在不添加项目ID到评论和子评论的情况下解决这个问题

Answer 1

我认为以下查询可以满足您的需求：

select *
from ls_comments c
where c.itemID = 9 or
      c.parentID in (select c2.commentId from ls_comments c2 where c2.itemId = 9)

Answer 2

递归Common Table Expression是否会为您提供您所追求的结果？

;with cte as 
(
    --Anchor
    select 
        commentid,
        ParentId
    from 
        LS_Commentes
    where
        ItemId = 9
    union all
    --Recursive member
    select 
        c.commentId,
        c.ParentId
    from
        LS_Commentes c join cte on c.ParentId = cte.CommentId

)
select * from cte

如果要在结果中包含更多列，请确保两个部分（Anchor和递归成员）具有相同的列。

说明：递归查询的锚点部分（第一个选择）选择ItemId = 9的所有行，第二个部分使用结果中的现有记录来包含满足它的crite的更多记录（ParentId = cte.CommentId）这一直持续到没有选择了更多。然后必须在结束时（在CTE定义之后）选择整个结果

Answer 3

我认为嵌入式SQL查询会很好

 SELECT * 
 FROM `LS_Commentes` 
 WHERE `ItemId` = '9' 
     AND `ParentID`= (SELECT `CommentID` FROM `LS_Commentes` WHERE `ItemId` = 9);

从一个表SQL服务器获取行和行

3 个答案: