I'm pretty sure I've asked about this before but can't find the right search terms just now to turn it up.
What I'd like are User Defined Constants so that I can just have a piece of SQL like

WHERE _InOut = IsExpenditure

and have IsExpenditure defined somewhere else

The reason is that in development I may well change (or have changed) my mind a few times and hunting down the variables is annoying.

I could get the same effect by having a UDF like

CREATE FUNCTION "IsExpenditure" ()
RETURNS VARCHAR(1) COLLATE "ANSI_CI"
BEGIN
RETURN '-';
END
VERSION 1.00

but I'm not sure about performance or maintenance

Roy Lambert