存储过程中根据@length int为几，@StringLing就=‘相应个数的0’

Declare @StringLing varchar(20)
Declare @ling int
  set @ling=@length
while @ling>0
Begin
  Set @StringLing=@StringLing+'0'
  set @ling=@ling-1
end
存储过程中根据@length int为几，@StringLing就=‘相应个数的0’
要怎么写！！！
存储过程中！
Set @Employeeid=@EmployeeSid+Right('000000'+convert(varchar(4),@beginNum),@length)--生成符合要求的人员编号需要将000000处替换成灵活的@StringLing