ODBC doesn't appear to allow for multiple cursors on the same result-set.^{5Is this right?} This would imply there can only be one active odbc_execute/3 (i.e. with a choice-point) on a prepared statement. Suppose we have a table age (name char(25), age integer) bound to the predicate age/2 we cannot write the code below without special precautions. The ODBC interface therefore creates a clone of a statement if it discovers the statement is being executed, which is discarded after the statement is finished.^{6The code is prepared to maintain a cache of statements. Practice should tell us whether it is worthwhile activating this.}

same_age(X, Y) :-
        age(X, AgeX),
        age(Y, AgeY),
        AgeX = AgeY.