表中数据 MySQL中or和and的用法
1 SELECT * from student WHERE id = 1 or id = 2 ANDage = 20; 2 3 查询结果是id = 2且age = 20或者id=1
1 SELECT * from student WHERE (id = 1 or id = 2 ) AND age = 20; 2 3 查询结果是 id=1或id=2 且age = 20