如何使用表名变量

[yjsng]

CREATE PROCEDURE dbo.insertDataD
@tablename nvarchar(12)='D20041010', @fldnum int, @tagname nvarchar(12)='yl001' , @val float=0, @state int = 0
AS
declare @table (FLDNO float NULL ,
TAGNAME varchar 20 ,
VALUE real NULL ,
STATE smallint NULL )
if exists(select tagname from @tablename where tagname = @tagname and fldno = @fldnum)
begin
update @tablename set value = @val
where tagname = @tagname and fldno = @fldnum and value<>@val
end
else
insert into dataD values(@fldnum, @tagname, @val, -1)
GO
请问如何使用表明变量是实现动态查询和插入？？？？

[finer]

你的变量连接不行啊

CREATE PROCEDURE dbo.insertDataD
@tablename nvarchar(12)='D20041010', @fldnum int, @tagname nvarchar(12)='yl001' , @val float=0, @state int = 0
AS
if exists(exec('select tagname from' + @tablename + 'where tagname= '+@tagname and fldno ='+@fldnum))
begin
exec(' update' + @tablename + 'set value = '+@val+' where tagname = '+@tagname+' and fldno = '+@fldnum+' and value<>'+@val)
end
else
exec('insert into ' + @tablename+'values('+@fldnum+','+@tagname+','+@val+', -1)')
GO

[fxcl2006]

可以参考：
create proc test_pro
@tablename varchar(50)
as
exec 'select * from ' + @tablename
go

[yjsng]

执行说 select from 附近有语法错误？？？？

[yjsng]

是不是要声明一个表变量？？我在sql帮助看到好象是要声明个表变量，但是我不知道怎么做？？？

[finer]

exec语句加个括号：

这样：
create procedure Finer_proce
@tabname varhcar(20)
as
exec('select * from '+@tabname)
go

这样就行了

[yjsng]

CREATE PROCEDURE dbo.insertDataD
@tablename nvarchar(12)='D20041010', @fldnum int, @tagname nvarchar(12)='yl001' , @val float=0, @state int = 0
AS
if exists(exec('select tagname from' + @tablename + 'where tagname= @tagname and fldno =@fldnum'))
begin
exec(' update' + @tablename + 'set value = @val where tagname = @tagname and fldno = @fldnum and value<>@val')
end
else
exec('insert into ' + @tablename+'values(@fldnum, @tagname, @val, -1)')
GO
帮我看看这样子为什么还是不行？？？

[fxcl2006]

哦，忘了括号。

[yjsng]

哪里的括号？？，说是 else附近和第四行“）”附近有语法错误？？？