BEGIN
declare @i int
set @i= (select COUNT(id) from dbo.tb_ErpCustomer)
while @i>0
begin
  UPDATE [dbo].[tb_ErpCustomer] SET  [Cus_Birthday] = CONVERT(varchar(100), CONVERT(datetime, Replace([Cus_Birthday],'A','')), 20)
  set @i=@i-1
end
END