不要讓mysql猶豫不決

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 1 DROP TABLE IF EXISTS `w1`; 2 CREATE TABLE `w1` ( 3   `waid` int(11) NOT NULL AUTO_INCREMENT, 4   `wa1` varchar(255) COLLATE utf8mb4_bin DEFAULT NULL, 5   `wa2` varchar(255) COLLATE utf8mb4_bin DEFAULT NULL, 6   PRIMARY KEY (`waid`) 7 ) ENGINE=MyISAM AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin; 8  9 -- ----------------------------10 -- Records of w111 -- ----------------------------12 INSERT INTO `w1` VALUES (‘1‘, ‘w1-1‘, ‘1‘);13 INSERT INTO `w1` VALUES (‘2‘, ‘w1-2‘, ‘2‘);

 1 DROP TABLE IF EXISTS `w2`; 2 CREATE TABLE `w2` ( 3   `wbid` int(11) NOT NULL AUTO_INCREMENT, 4   `wb1` varchar(255) COLLATE utf8mb4_bin DEFAULT NULL, 5   `wb2` varchar(255) COLLATE utf8mb4_bin DEFAULT NULL, 6   PRIMARY KEY (`wbid`) 7 ) ENGINE=MyISAM AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin; 8  9 -- ----------------------------10 -- Records of w211 -- ----------------------------12 INSERT INTO `w2` VALUES (‘1‘, ‘w2-1‘, ‘2‘);13 INSERT INTO `w2` VALUES (‘2‘, ‘w2-2‘, ‘2‘);

 

 1 SELECT * FROM w1 LEFT JOIN w2 ON w1.wa2=w2.wb2 2 SELECT * FROM w1 LEFT JOIN w2 ON w2.wb2=w1.wa2 3  4 SELECT * FROM w2 RIGHT JOIN w1 ON w1.wa2=w2.wb2 5 SELECT * FROM w2 RIGHT JOIN w1 ON w2.wb2=w1.wa2 6  7  8 SELECT * FROM w2 LEFT JOIN w1 ON w1.wa2=w2.wb2 9 SELECT * FROM w2 LEFT JOIN w1 ON w2.wb2=w1.wa210 11 SELECT * FROM w1 RIGHT JOIN w2 ON w1.wa2=w2.wb212 SELECT * FROM w1 RIGHT JOIN w2 ON w2.wb2=w1.wa213 14 15 SELECT * FROM w1 INNER JOIN w2 ON w1.wa2=w2.wb216 SELECT * FROM w1 INNER JOIN w2 ON w2.wb2=w1.wa217 SELECT * FROM w1 CROSS JOIN w2 ON w1.wa2=w2.wb218 SELECT * FROM w1 CROSS JOIN w2 ON w2.wb2=w1.wa219 20 SELECT * FROM w2 INNER JOIN w1 ON w1.wa2=w2.wb221 SELECT * FROM w2 INNER JOIN w1 ON w2.wb2=w1.wa222 SELECT * FROM w2 CROSS JOIN w1 ON w1.wa2=w2.wb223 SELECT * FROM w2 CROSS JOIN w1 ON w2.wb2=w1.wa2

 

不要讓mysql猶豫不決