issue_comments: 813162622

This almost works, but throws errors with some queries (anything with a rowid column for example) - it needs a bunch of test coverage. python def columns_for_query(conn, sql): rows = conn.execute('explain ' + sql).fetchall() table_rootpage_by_register = {r['p1']: r['p2'] for r in rows if r['opcode'] == 'OpenRead'} names_by_rootpage = dict( conn.execute( 'select rootpage, name from sqlite_master where rootpage in ({})'.format( ', '.join(map(str, table_rootpage_by_register.values())) ) ) ) columns_by_column_register = {} for row in rows: if row['opcode'] == 'Column': addr, opcode, table_id, cid, column_register, p4, p5, comment = row table = names_by_rootpage[table_rootpage_by_register[table_id]] columns_by_column_register[column_register] = (table, cid) result_row = [dict(r) for r in rows if r['opcode'] == 'ResultRow'][0] registers = list(range(result_row["p1"], result_row["p1"] + result_row["p2"] - 1)) all_column_names = {} for table in names_by_rootpage.values(): table_xinfo = conn.execute('pragma table_xinfo({})'.format(table)).fetchall() for row in table_xinfo: all_column_names[(table, row["cid"])] = row["name"] final_output = [] for r in registers: try: table, cid = columns_by_column_register[r] final_output.append((table, all_column_names[table, cid])) except KeyError: final_output.append((None, None)) return final_output