declare @tbnumber int
declare @tbname varchar(10)
declare @str varchar(1000)
select @tbnumber=convert(int,ceiling(rand()*5))
set @tbname='a'+convert(varchar(10),@tbnumber)
set @str=N'select * from '+@tbname
exec sp_executesql @str

------解决方案--------------------
declare @tbnumber int
declare @tbname varchar(10)---------declare @tbname nvarchar(10)
declare @str varchar(1000)---------declare @str nvarchar(1000)
select @tbnumber=convert(int,ceiling(rand()*5))
set @tbname='a'+convert(varchar(10),@tbnumber)
set @str=N'select * from '+@tbname
exec sp_executesql @str

上面对应修改即可``