动态sql语句基本语法
1 :普通SQL语句可以用Exec执行 eg: Select * from tableName
Exec('select * from tableName')
Exec sp_executesql N'select * from tableName' -- 请注意字符串前一定要加N 2:字段名,表名,数据库名之类作为变量时,必须用动态SQL eg:
declare @fname varchar(20)
set @fname = 'FiledName'
Select @fname from tableName -- 错误,不会提示错误,但结果为固定值FiledName,并非所要。
Exec('select ' + @fname + ' from tableName') -- 请注意 加号前后的 单引号的边上加空格 当然将字符串改成变量的形式也可
declare @fname varchar(20)
set @fname = 'FiledName' --设置字段名 declare @s varchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句会报错 declare @s Nvarchar(1000) -- 注意此处改为nvarchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句正确 3. 输出参数
declare @num int,
@sqls nvarchar(4000)
set @sqls='select count(*) from tableName'
exec(@sqls)
--如何将exec执行结果放入变量中? declare @num int,
@sqls nvarchar(4000)
set @sqls='select @a=count(*) from tableName '
exec sp_executesql @sqls,N'@a int output',@num output
select @num
1 :普通SQL语句可以用Exec执行 eg: Select * from tableName
Exec('select * from tableName')
Exec sp_executesql N'select * from tableName' -- 请注意字符串前一定要加N 2:字段名,表名,数据库名之类作为变量时,必须用动态SQL eg:
declare @fname varchar(20)
set @fname = 'FiledName'
Select @fname from tableName -- 错误,不会提示错误,但结果为固定值FiledName,并非所要。
Exec('select ' + @fname + ' from tableName') -- 请注意 加号前后的 单引号的边上加空格 当然将字符串改成变量的形式也可
declare @fname varchar(20)
set @fname = 'FiledName' --设置字段名 declare @s varchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句会报错 declare @s Nvarchar(1000) -- 注意此处改为nvarchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句正确 3. 输出参数
declare @num int,
@sqls nvarchar(4000)
set @sqls='select count(*) from tableName'
exec(@sqls)
--如何将exec执行结果放入变量中? declare @num int,
@sqls nvarchar(4000)
set @sqls='select @a=count(*) from tableName '
exec sp_executesql @sqls,N'@a int output',@num output
select @num
FROM cwsp a CROSS JOIN
(SELECT *
FROM fnGetFather(a.cwsp_nextlc) fnGetFather) aa
declare @sql as varchar(100)
declare @tb as varchar(10)
set @tb = '14'
set @sql = 'SELECT * FROM cwsp CROSS JOIN (SELECT * FROM fnGetFather_'+@tb+' fnGetFather) aa'
exec(@sql)
结果不能作为结果集去进行任何join操作
returns @t table(lc_id int,lc_type int,lc_jbr int,lc_spr int,lc_pid int,lc_zdje int)
as
begin
select @id = lc_pid from lcxx where lc_id = @id
while @@rowcount > 0
begin
insert into @t select * from lcxx where lc_id = @id
select @id = lc_pid from lcxx where lc_id = @id
end
return
end cwsp表
1 cwsp_id int 4 0
0 cwsp_xmmc varchar 50 1
0 cwsp_splb int 4 1
0 cwsp_spje numeric 9 1
0 cwsp_bz varchar 50 1
0 cwsp_ntime datetime 8 1
0 cwsp_ssbm char 4 1
0 cwsp_jbr char 10 1
0 cwsp_fs char 1 1
0 cwsp_nextlc int 4 1
0 cwsp_zzje numeric 9 1
0 cwsp_user int 4 1
0 cwsp_zt char 1 1
0 cwsp_sfwj char 1 1lcxx表
2 lc_id int 4 0
0 lc_type int 4 1
0 lc_jbr int 4 1
0 lc_spr int 4 1
0 lc_pid int 4 1
1 lc_zdje numeric 9 1