含有自增序列的表中使用truncate与delete的不同结果

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--Author：oliver QIN
--DATE：2015-12-21
--DESC：INDETITY（1，1）使用delete跟truncate后排序是怎么变化的
---==========================================建表
if exists(select * from sysobjects where ID=OBJECT_ID(N‘TB‘) AND XTYPE=‘u‘)
drop table TB
CREATE TABLE TB(ID INT IDENTITY(1,1),NAME NVARCHAR(100),dtDate datetime)

INSERT INTO TB SELECT ‘JACK‘,SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10) UNION ALL
               SELECT ‘TOM‘ ,SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10)

               
--===============建立存储过程（delete），先判断是否存在数据，如果存在就删除，然后插入数据，看序列的变化
go
IF((SELECT COUNT(*) FROM SYSOBJECTS WHERE ID=OBJECT_ID(N‘P_sample_DELETE‘) AND XTYPE=‘P‘)>0 )
DROP PROC P_sample_DELETE
GO
CREATE PROC P_sample_DELETE
as
begin
   if((select count(*) from TB WHERE dtDate=SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10))>0)
  begin
    delete from TB --WHERE  dtDate=SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10)    
  end
  INSERT INTO TB SELECT ‘JACK‘,SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10) UNION ALL
               SELECT ‘TOM‘ ,SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10)
end

GO
--===============建立存储过程（truncate），先判断是否存在数据，如果存在就删除，然后插入数据，看序列的变化


IF((SELECT COUNT(*) FROM SYSOBJECTS WHERE ID=OBJECT_ID(N‘P_sample_TRUNCATE‘) AND XTYPE=‘P‘)>0 )
DROP PROC P_sample_TRUNCATE
GO
CREATE PROC P_sample_TRUNCATE
as
begin
   if((select count(*) from TB WHERE dtDate=SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10))>0)
  begin
    TRUNCATE TABLE TB
  end
  INSERT INTO TB SELECT ‘JACK‘,SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10) UNION ALL
               SELECT ‘TOM‘ ,SUBSTRING(convert(varchar,dateadd(dd,-day(getdate()),getdate()),120),1,10)
end

--------------调用三次TRUNCATE 
EXEC P_sample_TRUNCATE 
EXEC P_sample_TRUNCATE 
EXEC P_sample_TRUNCATE

-------------调用三次DELETE 
EXEC P_sample_DELETE
EXEC P_sample_DELETE
EXEC P_sample_DELETE