Question

How would I go about generating a unique receipt number in the following range:
GA00000-GZ99999? I am not allowed to use the ‘I’ and ‘O’ letters so GI00000-GI99999 & GO00000-GO99999 would be excluded.

Ideally, I’d like to create this in T-SQL but can also do it in VB.Net. This number will be stored in SQL and I can access it prior to generating the next one. They do not have to be sequential.

Thanks.

Answer 1

I decided to do it as the following:

CREATE FUNCTION [dbo].[fn_generateReceiptNumber]() 
RETURNS NCHAR(7)
AS
BEGIN
    -- Declare the return variable here
    DECLARE @result NCHAR(7);   
    DECLARE @prefix NCHAR(1);
    DECLARE @suffix INT;
    DECLARE @currentMax NCHAR(7);

    SELECT @currentMax = MAX(ISNULL(fp.CustomReceiptNo, 'GA00001')) FROM dbo.FinPayment fp;

    SELECT @prefix = SUBSTRING(@currentMax,2,1);
    SELECT @suffix = CAST(SUBSTRING(@currentMax,3,7) AS INT);

    IF((@suffix + 1) > 99999)
    BEGIN
        SELECT @suffix = 0;
    END
    ELSE
    BEGIN
        SELECT @suffix = @suffix + 1;
    END

    IF(@suffix = 0)
    BEGIN
        IF(@prefix = 'Z')
        BEGIN
            RETURN -1;
        END
        ELSE
        BEGIN
            IF(NCHAR(UNICODE(@prefix)+1) IN ('I', 'O'))
            BEGIN
                SELECT @prefix = NCHAR(UNICODE(@prefix)+2);
            END
            ELSE
            BEGIN
                SELECT @prefix = NCHAR(UNICODE(@prefix)+1);
            END
        END
    END

    -- Return the result of the function
    SELECT @result = NCHAR(71) + @prefix + CAST(RIGHT('00000' + RTRIM(@suffix), 5) AS NCHAR(5));
    RETURN @result;

END
GO

Thank you everyone for the input.
Steve.