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Uses of m4 Macros
In what follows we will see a number of different situations in which macros prove useful. This is not to say
that there are no dangers involved. In addition to the traditional reasons for avoiding macros in languages
such as C we have the added problems of confusing the Sybase query optimizer in its development of
an effective query plan. In short, using a macro such as _eqn(au_ord,1) in a query instead of au_ord = 1
prevents the query plan from making use of any index on au_ord which might otherwise be used.
pletch@mcs.newpaltz.edu