Possible to implement a manual increment with just simple SQL INSERT?

Question

I have a primary key that I don\'t want to auto increment (for various reasons) and so I\'m looking for a way to simply increment that field when I INSERT. By simply, I mean

Answer 1

Any critiques of this? Works for me.

DECLARE @m_NewRequestID INT
        , @m_IsError BIT = 1
        , @m_CatchEndless INT = 0

WHILE @m_IsError = 1
    BEGIN TRY
        SELECT  @m_NewRequestID = (SELECT ISNULL(MAX(RequestID), 0) + 1 FROM Requests)

        INSERT INTO Requests (  RequestID
                                , RequestName
                                , Customer
                                , Comment
                                , CreatedFromApplication)
            SELECT  RequestID = @m_NewRequestID
                    , RequestName = dbo.ufGetNextAvailableRequestName(PatternName)
                    , Customer = @Customer
                    , Comment = [Description]
                    , CreatedFromApplication = @CreatedFromApplication
                FROM    RequestPatterns
                WHERE   PatternID = @PatternID

        SET @m_IsError = 0
    END TRY
    BEGIN CATCH
        SET @m_IsError = 1
        SET @m_CatchEndless = @m_CatchEndless + 1
        IF @m_CatchEndless > 1000
            THROW 51000, '[upCreateRequestFromPattern]: Unable to get new RequestID', 1
    END CATCH