我看到有些人确实这样加入
@H_403_6@SELECT * FROM table1 JOIN table 2 ON table1_id = table2_id
在某些人这样做的地方
@H_403_6@SELECT * FROM table1 WHERE table1.table1_id = tabl2.table2_id;
有什么区别,什么更有效和有益
最佳答案
这就是为什么
@H_403_6@SELECT * FROM table1 INNER JOIN table 2 ON table1_id = table2_id SELECT * FROM table1 LEFT JOIN table 2 ON table1_id = table2_id SELECT * FROM table1 RIGHT JOIN table 2 ON table1_id = table2_id SELECT * FROM table1 FULL OUTER JOIN table 2 ON table1_id = table2_id