SQL Server

I am trying to make an Update Stored Procedure that will Null a value if a null is passed in the parameter. So I made the defaults a value we would never use "~" then did an IIF to determine if a null was passed but my logic is not working. Any advise on how to achieve what I am trying? Here is my code...

/****** Object:  StoredProcedure [dbo].[USP_Account_Update2]    Script Date: 11/6/2019 1:17:05 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO


-- =============================================
-- Author:        Jim Flagg
-- Create date: 10/30/19
-- Description:    Updates the Accountnote table
-- =============================================
ALTER PROCEDURE [dbo].[USP_Account_Update2]
    -- Add the parameters for the stored procedure here
    --<@Param1, sysname, @p1> <Datatype_For_Param1, , int> = <Default_Value_For_Param1, , 0>,
    --<@Param2, sysname, @p2> <Datatype_For_Param2, , int> = <Default_Value_For_Param2, , 0>
    @AccountID                    bigint,             -- Read Only To seek on.
    @BindingKey                   varchar(10) = '~',
    @AcctNum                      varchar(10) = '~',
    @ClientId                     bigint = null,
    @AcctMark                     char(1) = '~',
    @AcctLink                     varchar(30) = '~',
    @TypeCodeId                   bigint = null,
    @PlacementId                  varchar(21) = '~',
    @FwdrSiteCd                   varchar(10) = '~',
    @FirmSiteCd                   varchar(10) = '~',
    @AuxNum                       varchar(30) = '~',
    @OtherAcctNum                 varchar(30) = '~',
    @OrigUserCodeId               bigint = null,
    @RespUserCodeId               bigint = null,
    @AssignedFromCodeId           bigint = null,
    @RcvAttyCodeId                bigint = null,
    @RcvAttyDate                  date = '1899-12-30',
    @OtherPartyCodeId             bigint = null,
    @ClientAgentCodeId            bigint = null,
    @OrigCredNote                 varchar(max) = '~',
    @TrxNote                      varchar(max) = '~',
    @Remarks                      varchar(max) = '~',
    @ClientCode_Translation       varchar(100) = '~',
    @TypeCode_Translation         varchar(100) = '~',
    @OrigCode_Translation         varchar(100) = '~',
    @RespCode_Translation         varchar(100) = '~',
    @AssignedFromCode_Translation varchar(100) = '~',
    @RcvAttyCode_Translation      varchar(100) = '~',
    @OtherPartyCode_Translation   varchar(100) = '~',
    @ClientAgentCode_Translation  varchar(100) = '~',
    @JST_PkARoot                  varchar(8) = '~'
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Insert statements for procedure here
    if @AccountId > 0
    begin
      Update Account
      Set
        BindingKey                   = iif(@BindingKey <> null, @BindingKey, BindingKey)                                                       ,
        AcctNum                      = iif(@AcctNum <> '~', @AcctNum, AcctNum)                                                                 ,
        ClientId                     = iif(@ClientId <> null, @ClientId, ClientId)                                                             ,
        AcctMark                     = iif(@AcctMark <> '~', @AcctMark, AcctMark)                                                              ,
        AcctLink                     = iif(@AcctLink <> '~', @AcctLink, AcctLink)                                                              ,
        TypeCodeId                   = iif(@TypeCodeId <> null, @TypeCodeId, TypeCodeId)                                                       ,
        PlacementId                  = iif(@PlacementId <> null, @PlacementId, PlacementId)                                                    ,
        FwdrSiteCd                   = iif(@FwdrSiteCd <> '~', @FwdrSiteCd, FwdrSiteCd)                                                        ,
        FirmSiteCd                   = iif(@FirmSiteCd <> '~', @FirmSiteCd, FirmSiteCd)                                                           ,
        AuxNum                       = iif(@AuxNum <> '~', @AuxNum, AuxNum)                                                                       ,
        OtherAcctNum                 = iif(@OtherAcctNum <> '~', @OtherAcctNum, OtherAcctNum)                                                   ,
        OrigUserCodeId               = iif(@OrigUserCodeId <> null, @OrigUserCodeId, OrigUserCodeId)                                           ,
        RespUserCodeId               = iif(@RespUserCodeId <> null, @RespUserCodeId, RespUserCodeId)                                           ,
        AssignedFromCodeId           = iif(@AssignedFromCodeId <> null, @AssignedFromCodeId, AssignedFromCodeId)                               ,
        RcvAttyCodeId                = iif(@RcvAttyCodeId <> null, @RcvAttyCodeId, RcvAttyCodeId)                                               ,
        RcvAttyDate                  = iif(@RcvAttyDate <> '1899-12-30', @RcvAttyDate, RcvAttyDate)                                               ,
        OtherPartyCodeId             = iif(@OtherPartyCodeId <> null, @OtherPartyCodeId, OtherPartyCodeId)                                       ,
        ClientAgentCodeId            = iif(@ClientAgentCodeId <> null, @ClientAgentCodeId, ClientAgentCodeId)                                   ,
        OrigCredNote                 = iif(@OrigCredNote <> '~', @ClientAgentCodeId, ClientAgentCodeId)                                           ,
        TrxNote                      = iif(@TrxNote <> '~', @TrxNote, TrxNote)                                                                   ,
        Remarks                      = iif(@Remarks <> '~', @Remarks, Remarks)                                                                   ,
        ClientCode_Translation       = iif(@ClientCode_Translation <> '~', @ClientCode_Translation, ClientCode_Translation)                    ,
        TypeCode_Translation         = iif(@TypeCode_Translation <> '~', @TypeCode_Translation, TypeCode_Translation)                           ,
        OrigCode_Translation         = iif(@OrigCode_Translation <> '~', @OrigCode_Translation, OrigCode_Translation)                           ,
        RespCode_Translation         = iif(@RespCode_Translation <> '~', @RespCode_Translation, RespCode_Translation)                           ,
        AssignedFromCode_Translation = iif(@AssignedFromCode_Translation <> '~', @AssignedFromCode_Translation, AssignedFromCode_Translation)  ,
        RcvAttyCode_Translation      = iif(@RcvAttyCode_Translation <> '~', @RcvAttyCode_Translation, RcvAttyCode_Translation)                   ,
        OtherPartyCode_Translation   = iif(@OtherPartyCode_Translation <> '~', @OtherPartyCode_Translation, OtherPartyCode_Translation)           ,
        ClientAgentCode_Translation  = iif(@ClientAgentCode_Translation <> '~', @ClientAgentCode_Translation, ClientAgentCode_Translation)       ,
        JST_PkARoot                  = iif(@JST_PkARoot <> '~', @JST_PkARoot, JST_PkARoot)
      Where AccountID = @AccountID
      -- Code here for Updating Dependant Orphans or we could put the Orphan updates in a On Update Trigger.
    end
END

Code (SQL):

 

Never Mind. I figured out how to get it to work. I just used a " Is Null or <> '~' ".

Thanks,

Jim