protected Symbol visitQuerySpecification(QuerySpecification node, SelectAnalysis context) {
// visit the from first, since this qualifies the select
int numTables = node.getFrom() == null ? 0 : node.getFrom().size();
if (numTables != 1) {
throw new SQLParseException(
"Only exactly one table is allowed in the from clause, got: " + numTables
);
}
process(node.getFrom().get(0), context);