mysql INNER/LEFT/RIGHT JOIN区别

Posted 2021-02-04 love_best

 1、创建table

DROP TABLE IF EXISTS `tab_id_index`;
CREATE TABLE `tab_id_index` (
  `id` int(11) NOT NULL DEFAULT \'0\',
  `name` varchar(10) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

-- ----------------------------
-- Records of tab_id_index
-- ----------------------------
INSERT INTO `tab_id_index` VALUES (\'1\', \'3\', \'12\');
INSERT INTO `tab_id_index` VALUES (\'2\', \'3\', \'12\');
INSERT INTO `tab_id_index` VALUES (\'3\', \'3\', \'12\');
INSERT INTO `tab_id_index` VALUES (\'5\', \'4\', \'14\');

DROP TABLE IF EXISTS `tab_no_index`;
CREATE TABLE `tab_no_index` (
  `id` int(11) NOT NULL DEFAULT \'0\',
  `name` varchar(10) DEFAULT NULL,
  `age` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

-- ----------------------------
-- Records of tab_no_index
-- ----------------------------
INSERT INTO `tab_no_index` VALUES (\'1\', \'1\', \'12\');
INSERT INTO `tab_no_index` VALUES (\'2\', \'1\', \'12\');
INSERT INTO `tab_no_index` VALUES (\'3\', \'3\', \'12\');
INSERT INTO `tab_no_index` VALUES (\'4\', \'6\', \'14\');

 

2、sql查询

select * from tab_id_index a,tab_no_index b where a.id = b.id;

同：

select * from tab_id_index a INNER JOIN tab_no_index b ON a.id = b.id;

 

select * from tab_id_index a LEFT JOIN tab_no_index b ON a.id = b.id;

同：

select * from tab_id_index a LEFT OUTER JOIN tab_no_index b ON a.id = b.id;

 

select * from tab_id_index a RIGHT JOIN tab_no_index b ON a.id = b.id;

同：

select * from tab_id_index a RIGHT OUTER JOIN tab_no_index b ON a.id = b.id;