Sql StoreProcedure

ALTER procedure [dbo].[Emp_Registration_sp]
@common nvarchar(1)='',
@Emp_Id int =0,
@Emp_Name nvarchar(50)='',
@Emp_LastName nvarchar(50)='',
@Emp_EmailId nvarchar(50)='',
@Emp_Password nvarchar(50)='',
@Emp_RetypePassword nvarchar(50)='',
@Emp_Country nvarchar(50)='',
@Emp_State nvarchar(50)='',
@Emp_City nvarchar(50)='',
@Emp_Qualification nvarchar(50)='',
@Emp_Address nvarchar(MAX)='',
@Emp_DateOfBirth nvarchar(50)='',
@Emp_Sex nchar(10)=''
as
if @common ='S'
begin
Select * from Emp_Registraion
end
else if @common ='I'
begin
select @Emp_Id=(MAX(Emp_Id)+1)from Emp_Registraion
insert into Emp_Registraion (Emp_Name,Emp_LastName,Emp_EmailId,Emp_Password,Emp_RetypePassword,Emp_Country,Emp_State,Emp_City,Emp_Qualification,Emp_Address,Emp_DateOfBirth,Emp_Sex)values
(@Emp_Name,@Emp_LastName,@Emp_EmailId,@Emp_Password,@Emp_RetypePassword,@Emp_Country,@Emp_State,@Emp_City,@Emp_Qualification,@Emp_Address,@Emp_DateOfBirth,@Emp_Sex)
end
else if @common='U'
begin
Update Emp_Registraion set Emp_Name=@Emp_Name,Emp_LastName=@Emp_LastName,Emp_EmailId=@Emp_EmailId,Emp_Password=@Emp_Password,Emp_RetypePassword=@Emp_RetypePassword,Emp_Country=@Emp_Country,Emp_State=@Emp_State,Emp_City=@Emp_City,
Emp_Qualification=@Emp_Qualification,Emp_Address=@Emp_Address,Emp_DateOfBirth=@Emp_DateOfBirth,Emp_Sex=@Emp_Sex where Emp_Id=@Emp_Id
end
else if @common='D'
begin
Delete from Emp_Registraion where Emp_Id=@Emp_Id
end