求一个PROC

Question

Create proc DelRecorder
@tblname varchar(50),
@tblkey int,
@tblwhere int
as
begin
delete @tblname where @tblkey=@tblwhere
end消息 1087，级别 15，状态 2，过程 DelRecorder，第 7 行
必须声明表变量 "@tblname"。
这样创建,为什么会出错

Answer 1

begin
exec('delete '+@tblname+' where '+@tblkey+'='+@tblwhere)
end

Answer 2

Create proc DelRecorder
@tblname varchar(50),
@tblkey int,
@tblwhere int
as
begin
exec('delete '+ @tblname+'  where '+ @tblkey+'='+@tblwhere)
end

Answer 3

begin
exec('delete from'+@tblname+' where '+@tblkey+'='+@tblwhere)
end

Answer 4

Create proc DelRecorder
@tblname varchar(50),
@tblkey int,
@tblwhere int
as
begin
exec('delete '+@tblname+' where '+@tblkey+'='+@tblwhere)
end