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最新推荐文章于 2025-12-31 22:48:07 发布

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#sql server #insert #table #microsoft #books #脚本

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本文介绍如何使用Transact-SQL脚本查找Microsoft SQL Server中由于删除数据导致的身份值序列中的空缺。通过设置示例展示了如何定位这些间隙，并提供了一段具体的SQL脚本来演示整个过程。

使 Microsoft® SQL Server™ 在返回指定的行数之后停止处理查询。

语法

SET ROWCOUNT { number | @number_var }

B. 使用一般语法查找标识值中的差距

下面的示例显示一般的语法，当删除数据时，可以使用该语法查找标识值中的差距。

说明下面的 Transact-SQL 脚本中的第一部分只用作示范说明。可以运行以下面的注释开始的 Transact-SQL 脚本：- - Create the img table.

-- Here is the generic syntax for finding identity value gaps in data.
-- This is the beginning of the illustrative example.
SET IDENTITY_INSERT tablename ON

DECLARE @minidentval column_type
DECLARE @nextidentval column_type
SELECT @minidentval = MIN(IDENTITYCOL) FROM tablename
IF @minidentval = IDENT_SEED('tablename')
   SELECT @nextidentval = MIN(IDENTITYCOL) + IDENT_INCR('tablename')
   FROM tablename t1
   WHERE IDENTITYCOL BETWEEN IDENT_SEED('tablename') AND 
      MAX(column_type) AND
      NOT EXISTS (SELECT * FROM tablename t2
         WHERE t2.IDENTITYCOL = t1.IDENTITYCOL + 
            IDENT_INCR('tablename'))
ELSE
   SELECT @nextidentval = IDENT_SEED('tablename')
SET IDENTITY_INSERT tablename OFF
-- Here is an example to find gaps in the actual data.
-- The table is called img and has two columns: the first column 
-- called id_num, which is an increasing identification number, and the 
-- second column called company_name.
-- This is the end of the illustration example.

-- Create the img table.
-- If the img table already exists, drop it.
-- Create the img table.
IF EXISTS(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES 
      WHERE TABLE_NAME = 'img')
   DROP TABLE img
GO
CREATE TABLE img (id_num int IDENTITY(1,1), company_name sysname)
INSERT img(company_name) VALUES ('New Moon Books')
INSERT img(company_name) VALUES ('Lucerne Publishing')
-- SET IDENTITY_INSERT ON and use in img table.
SET IDENTITY_INSERT img ON

DECLARE @minidentval smallint
DECLARE @nextidentval smallint
SELECT @minidentval = MIN(IDENTITYCOL) FROM img
 IF @minidentval = IDENT_SEED('img')
    SELECT @nextidentval = MIN(IDENTITYCOL) + IDENT_INCR('img')
    FROM img t1
    WHERE IDENTITYCOL BETWEEN IDENT_SEED('img') AND 32766 AND
      NOT    EXISTS (SELECT * FROM img t2
          WHERE t2.IDENTITYCOL = t1.IDENTITYCOL + IDENT_INCR('img'))
 ELSE
    SELECT @nextidentval = IDENT_SEED('img')
SET IDENTITY_INSERT img OFF