Re: Bison conflict ?

Richard,
Consider changing these rules:
exp_list => expression;
expression => '(' query_specification ')';
query_list => '(' query_list ')';
query_list => query_specification;

Whether the query_spec in your statement #3 should reduce to exp_list
or query_list will depend on the particular SQL dialect you are
working with, especially the treatment of redundant parentheses. You
may also consider creating an extra nonterminal such as
exp_or_query_list.

Hope it helps.
Y.