executesql 是 SQL Server 的一个存储过程，用于执行一个 SQL 语句。

语法：

sp_executesql [@stmt =] stmt
[
     {, [@params =] N'@parameter_name data_type [,...n]' }
     {, [@param1 =] 'value1' [,...n] }
]

下面是在做一个连环复制插入数据表中相同数据事例，用到executesql

CREATE TABLE table1 (
id int IDENTITY (1, 1) NOT NULL ,
[title] varchar(50)
)

insert into table1(title) values('11')
insert into table1(title) values('22')
insert into table1(title) values('33')
insert into table1(title) values('44')

select * from table1

-------------------------------------------------------------

declare @id int
declare @j int
declare @k int
declare @strsql nvarchar(400)---一定要设为nvarchar,不是varchar

select @k=count(1) from table1
set @j=0
while (@j<@k)
begin

set @strsql='select @id=id from table1 where id not in(select top '+cast(@j as varchar)+' id from table1) order by id desc'
   --print @strsql

EXEC sp_executesql @strsql,N'@id int output',@id output

insert into table1(title) select (title + '_' + cast(@@identity + 1 as varchar)) from table1
where id=@id

set @j=@j+1
end

不知道为什么@strsql 非要设为nvarchar,浪费了几个小时时间，做个记录，