关于on子句中or的处理问题

[hmk114]

在yacc_sql.y中，on子句和where子句共用符号condition_list：

TDB/src/server/query_engine/parser/yacc_sql.y

Lines 1076 to 1095 in a09b6b1

	condition_list:
	/* empty */ {
	$$ = nullptr;
	} | condition {
	$$ = new WhereConditions;
	$$->conditions.emplace_back(*$1);
	delete $1;
	} | condition AND condition_list {
	$$ = $3;
	$$->type = ConjunctionType::AND;
	$$->conditions.emplace_back(*$1);
	delete $1;
	} | condition OR condition_list {
	$$ = $3;
	$$->type = ConjunctionType::OR;
	$$->conditions.emplace_back(*$1);
	delete $1;
	}
	;

但是创建JoinSqlNode时，condition_list中的ConjunctionType type属性被丢弃了（JoinSqlNode中没有type字段）：

TDB/src/server/query_engine/parser/yacc_sql.y

Lines 1031 to 1053 in a09b6b1

	join_list:
	/* empty */
	{
	$$ = nullptr;
	}
	| INNER JOIN rel_alias join_conditions join_list{
	if ($5 != nullptr) {
	$$ = $5;
	} else {
	$$ = new std::vector<JoinSqlNode>;
	}
	JoinSqlNode* joinSqlNode = new JoinSqlNode;
	joinSqlNode->relation = *$3;
	if ($4 != nullptr) {
	joinSqlNode->join_conditions.swap($4->conditions);
	std::reverse(joinSqlNode->join_conditions.begin(), joinSqlNode->join_conditions.end());
	}
	delete $4;
	$$->emplace_back(*joinSqlNode);
	delete joinSqlNode;
	delete $3;
	}
	;

最后，在创建select_stmt对象时，FilterStmt对象中的ConjunctionType conjunction_type_字段也未被赋值（后面对where和having子句的处理则正确进行了赋值）：

TDB/src/server/query_engine/analyzer/statement/select_stmt.cpp

Lines 257 to 271 in a09b6b1

	std::vector<FilterStmt *> join_filter_stmts;
	for (auto& join_list :select_sql.join_lists) {
	FilterStmt *join_filter_stmt = nullptr;
	rc = FilterStmt::create(db,
	default_table,
	&table_map,
	join_list.join_conditions.data(),
	static_cast<int>(join_list.join_conditions.size()),
	join_filter_stmt);
	join_filter_stmts.emplace_back(join_filter_stmt);
	if (rc != RC::SUCCESS) {
	LOG_WARN("cannot construct filter stmt");
	return rc;
	}
	}

因此对于on中含有or的情况，目前的语法解析器虽然不会报错，但是解析结果并不能区分or和and两种不同的情况。
例如，下面两条语句会得到相同的语法树（都是and）：

select * from join_table_1 inner join join_table_2 on join_table_1.id=join_table_2.id and join_table_2.num>13;
select * from join_table_1 inner join join_table_2 on join_table_1.id=join_table_2.id or join_table_2.num>13;

这容易引起困惑。如果是为了lab3实现方便，有意限制on条件仅能由and连接，或许应该在文档里更明确地说明一下，或者在语法解析时就限制不能出现or？

[ycycse]

是的 主要还是因为lab3只考虑and的连接情况，就没有做对应实现
之后会考虑加上