SQL Server 内连接使用 WITH(NOLOCK)答案

【问题标题】：SQL Server Inner Join using WITH(NOLOCK)SQL Server 内连接使用 WITH(NOLOCK)
【发布时间】：2016-03-08 01:08:45
【问题描述】：

我有一个数据库查询：

DECLARE @Pager_PageNumber AS INT, @Pager_PageSize AS INT; 

SET @Pager_PageNumber = 1; 
SET @Pager_PageSize = 12; 

SELECT 
    [Name], [Description], [Table1ID], [VersionNo], [Status] 
FROM
    (SELECT 
         CAST(Table1.name AS VARCHAR(MAX)) As [Name],
         CAST(Table1.description AS VARCHAR(MAX)) AS [Description],
         CAST(CAST(Table1.Table1_ID AS DECIMAL(18,0)) AS VARCHAR(MAX)) AS [Table1ID],
         CAST(CAST(Table1.VERSION_NO AS DECIMAL(18,0)) AS VARCHAR(MAX)) AS [VersionNo],
         CAST(Table2.br_status AS VARCHAR(MAX)) AS [Status]  
    FROM  
        Table1 WITH (NOLOCK)
    INNER JOIN 
        (SELECT 
             Table1_id, MAX(version_no) as version_no
         FROM Table1
         WHERE Table1.status = '00002'
         GROUP BY Table1_id) AS BR WITH (NOLOCK) ON Table1.Table1_id = BR.Table1_id 
                                                 AND BR.version_no = Table1.version_no 
    INNER JOIN 
        Table2 WITH (NOLOCK) ON Table1.status = Table2.br_status_code) A 
ORDER BY 
    [Name], [Description], [Table1ID], [VersionNo], [Status] 
    OFFSET ((@Pager_PageNumber - 1) * @Pager_PageSize) ROWS 
       FETCH NEXT @Pager_PageSize ROWS ONLY;

SELECT COUNT(*) 
FROM
    (SELECT 
         CAST(Table1.name AS VARCHAR(MAX)) AS [Name],
         CAST(Table1.description AS VARCHAR(MAX)) AS [Description],
         CAST(CAST(Table1.Table1_ID AS DECIMAL(18,0)) AS VARCHAR(MAX)) AS [Table1ID],
         CAST(CAST(Table1.VERSION_NO AS DECIMAL(18,0)) AS VARCHAR(MAX)) As [VersionNo],
         CAST(Table2.br_status AS VARCHAR(MAX)) AS [Status]  
    FROM  
        Table1 WITH (NOLOCK)  
    INNER JOIN
        (SELECT Table1_id, MAX(version_no) as version_no
         FROM Table1
         WHERE Table1.status = '00002'
         GROUP BY Table1_id) AS BR WITH (NOLOCK) ON Table1.Table1_id = BR.Table1_id 
                                                 AND BR.version_no = Table1.version_no 
    INNER JOIN 
        Table2 WITH (NOLOCK) ON Table1.status = Table2.br_status_code) A;

在 SQL Server 中，我在附近遇到错误：BR WITH (NOLOCK) 那：

关键字“WITH”附近的语法不正确。关键字“with”附近的语法不正确。如果这个语句是一个公用表表达式、一个 xmlnamespaces 子句或一个更改跟踪上下文子句，则前面的语句必须以分号结束。

但根据我对来源like 的理解，语法如下

SELECT 
    first_name, last_name,
FROM 
    dbo.person p WITH (NOLOCK)
JOIN 
    dbo.employee e WITH (NOLOCK) ON e.person_id = p.person_id
WHERE 
    p.person_id = 1;

所以，我的查询看起来差不多。

此外，当我删除 BR WITH (NOLOCK) 旁边的 WITH (NOLOCK) 时，即我的内部连接查询，查询运行良好。关于我可能遗漏的任何想法？

PS：我的 DB 兼容级别是 110。

【问题讨论】：

请在发布前格式化您的查询 - sql-format.com
设置Bad Habits to kick - putting NOLOCK everywhere - 不推荐在任何地方使用它 - 恰恰相反！
我建议尽可能删除 WITH (NOLOCK)。此语句允许您包含脏读，这意味着它可能会为您的事务生成错误，向用户提供从未提交的数据，或导致用户看到两次记录（或根本看不到）。更多信息请见：msdn.microsoft.com/en-GB/library/ms187373.aspx.
@SyedOsamaMaruf，首先给了你答案，甚至格式化了你的代码，我得到的只是一个赞成票哈哈:) 我肯定会领导什么marc_s 是建议。

标签： sql sql-server join inner-join self-join

【解决方案1】：

您将with (nolock) 应用于表，而不是子查询。所以，而不是：

(SELECT Table1_id, MAX(version_no) as version_no
 FROM Table1
 where Table1.status='00002'
 GROUP BY Table1_id
) as BR WITH (NOLOCK)

你会写：

(SELECT Table1_id, MAX(version_no) as version_no
 FROM Table1 WITH (NOLOCK)
 where Table1.status='00002'
 GROUP BY Table1_id
) BR

【讨论】：

【解决方案2】：

随便放

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

在您查询之前。 NOLOCK 行为将用于查询中的所有表。使用提示 NOLOCK 只是意味着对特定表使用 READ UNCOMMITTED 事务隔离级别。

【讨论】：

同志，很高兴在这里见到你；）
哦，太好了，现在我有足够的声誉来评论帖子了 :) 你好 :)

【解决方案3】：

错误是您在 GROUP BY 子句中有WITH (NOLOCK)，而它应该只在 FROM 子句中：

 GROUP BY Table1_id) as  BR WITH (NOLOCK)

应该是

FROM Table1 WITH (NOLOCK)

这是您发布的代码底部的 3 行。它也出现在更上方。

你的代码有更正（我想我都明白了！）：

DECLARE @Pager_PageNumber AS INT, @Pager_PageSize AS INT; SET @Pager_PageNumber = 1; SET @Pager_PageSize = 12; SELECT [Name],[Description],[Table1ID],[VersionNo],[Status] FROM(SELECT CAST(Table1.name AS VARCHAR(MAX)) As [Name],CAST(Table1.description AS VARCHAR(MAX)) As [Description],CAST(CAST(Table1.Table1_ID AS DECIMAL(18,0)) AS VARCHAR(MAX)) As
 [Table1ID],CAST(CAST(Table1.VERSION_NO AS DECIMAL(18,0)) AS VARCHAR(MAX)) As [VersionNo],
 CAST(Table2.br_status AS VARCHAR(MAX)) As [Status]  FROM  Table1 WITH (NOLOCK)
  INNER JOIN (SELECT Table1_id, MAX(version_no) as version_no
    FROM Table1 WITH (NOLOCK)
    where Table1.status='00002'
    GROUP BY Table1_id) as BR ON Table1.Table1_id = BR.Table1_id AND BR.version_no=Table1.version_no 
    INNER JOIN Table2 WITH (NOLOCK) ON Table1.status = Table2.br_status_code )A 
    ORDER BY [Name],[Description],[Table1ID],[VersionNo],[Status] OFFSET ((@Pager_PageNumber - 1) * @Pager_PageSize)
     ROWS FETCH NEXT @Pager_PageSize ROWS ONLY;SELECT COUNT(*) FROM(SELECT CAST(Table1.name AS VARCHAR(MAX)) As 
     [Name],CAST(Table1.description AS VARCHAR(MAX)) As [Description],CAST(CAST(Table1.Table1_ID AS DECIMAL(18,0)) 
     AS VARCHAR(MAX)) As [Table1ID],CAST(CAST(Table1.VERSION_NO AS DECIMAL(18,0)) AS VARCHAR(MAX)) As [VersionNo],
     CAST(Table2.br_status AS VARCHAR(MAX)) As [Status]  FROM  Table1 WITH (NOLOCK)  INNER JOIN
      (SELECT Table1_id, MAX(version_no) as version_no
    FROM Table1 WITH (NOLOCK)
    where Table1.status='00002'
    GROUP BY Table1_id) as  BR
     ON Table1.Table1_id = BR.Table1_id AND BR.version_no=Table1.version_no INNER JOIN Table2 
     WITH (NOLOCK) ON Table1.status = Table2.br_status_code )A;

【讨论】：

【解决方案4】：

不能移动WITH (NOLOCK)，所以它在子查询里面吗？

本质上，这...

INNER JOIN ( SELECT Table1_id
                                       ,MAX(version_no) AS version_no
                                 FROM   Table1 WITH ( NOLOCK )
                                 WHERE  Table1.status = '00002'
                                 GROUP BY Table1_id
                               ) AS BR

完整代码

DECLARE @Pager_PageNumber AS INT
   ,@Pager_PageSize AS INT;
SET @Pager_PageNumber = 1;
SET @Pager_PageSize = 12;
SELECT  [Name]
       ,[Description]
       ,[Table1ID]
       ,[VersionNo]
       ,[Status]
FROM    ( SELECT    CAST(Table1.name AS VARCHAR(MAX)) AS [Name]
                   ,CAST(Table1.description AS VARCHAR(MAX)) AS [Description]
                   ,CAST(CAST(Table1.Table1_ID AS DECIMAL(18, 0)) AS VARCHAR(MAX)) AS [Table1ID]
                   ,CAST(CAST(Table1.VERSION_NO AS DECIMAL(18, 0)) AS VARCHAR(MAX)) AS [VersionNo]
                   ,CAST(Table2.br_status AS VARCHAR(MAX)) AS [Status]
          FROM      Table1 WITH ( NOLOCK )
                    INNER JOIN ( SELECT Table1_id
                                       ,MAX(version_no) AS version_no
                                 FROM   Table1 WITH ( NOLOCK )
                                 WHERE  Table1.status = '00002'
                                 GROUP BY Table1_id
                               ) AS BR ON Table1.Table1_id = BR.Table1_id
                                          AND BR.version_no = Table1.version_no
                    INNER JOIN Table2 WITH ( NOLOCK ) ON Table1.status = Table2.br_status_code
        ) A
ORDER BY [Name]
       ,[Description]
       ,[Table1ID]
       ,[VersionNo]
       ,[Status]
       OFFSET ( ( @Pager_PageNumber - 1 ) * @Pager_PageSize ) ROWS FETCH NEXT @Pager_PageSize
        ROWS ONLY;
SELECT  COUNT(*)
FROM    ( SELECT    CAST(Table1.name AS VARCHAR(MAX)) AS [Name]
                   ,CAST(Table1.description AS VARCHAR(MAX)) AS [Description]
                   ,CAST(CAST(Table1.Table1_ID AS DECIMAL(18, 0)) AS VARCHAR(MAX)) AS [Table1ID]
                   ,CAST(CAST(Table1.VERSION_NO AS DECIMAL(18, 0)) AS VARCHAR(MAX)) AS [VersionNo]
                   ,CAST(Table2.br_status AS VARCHAR(MAX)) AS [Status]
          FROM      Table1 WITH ( NOLOCK )
                    INNER JOIN ( SELECT Table1_id
                                       ,MAX(version_no) AS version_no
                                 FROM   Table1 WITH ( NOLOCK )
                                 WHERE  Table1.status = '00002'
                                 GROUP BY Table1_id
                               ) AS BR ON Table1.Table1_id = BR.Table1_id
                                          AND BR.version_no = Table1.version_no
                    INNER JOIN Table2 WITH ( NOLOCK ) ON Table1.status = Table2.br_status_code
        ) A;

【讨论】：

【解决方案5】：

DECLARE @Pager_PageNumber AS INT,
        @Pager_PageSize AS INT;

SELECT @Pager_PageNumber = 1, @Pager_PageSize = 12;

SELECT [Name],[Description],[BRMAINID],[VersionNo],[Status]
FROM (
    SELECT
        Table1.name As [Name],
        Table1.[description] As [Description],
        Table1.Table1_ID AS [BRMAINID],
        Table1.VERSION_NO AS [VersionNo],
        Table2.br_status AS [Status]
    FROM dbo.Table1 WITH(NOLOCK)
    JOIN (
        SELECT Table1_id, MAX(version_no) as version_no
        FROM dbo.Table1 WITH(NOLOCK)
        WHERE Table1.[status] = '00002'
        GROUP BY Table1_id
    ) AS BR ON Table1.Table1_id = BR.Table1_id AND BR.version_no=Table1.version_no 
    JOIN dbo.Table2 WITH(NOLOCK) ON Table1.status = Table2.br_status_code
) A 
ORDER BY [Name], [Description], [BRMAINID], [VersionNo], [Status]
    OFFSET ((@Pager_PageNumber - 1) * @Pager_PageSize)
    ROWS FETCH NEXT @Pager_PageSize ROWS ONLY

SELECT COUNT(*)
FROM dbo.Table1 WITH(NOLOCK)
JOIN (
    SELECT Table1_id, MAX(version_no) as version_no
    FROM dbo.Table1 WITH(NOLOCK)
    where Table1.[status] = '00002'
    GROUP BY Table1_id
) as BR ON Table1.Table1_id = BR.Table1_id AND BR.version_no=Table1.version_no
JOIN dbo.Table2 WITH(NOLOCK) ON Table1.status = Table2.br_status_code

试试吧……

【讨论】：