SQL 去除表中重复数据

方法1： 数据太多会卡

select j1.* from vkool_jxs j1, vkool_jxs j2 
where j1.id > j2.id 
and j1.jxs_name=j2.jxs_name 
and j1.jxs_type=j2.jxs_type;

方法2： 速度块

SELECT
	* 
FROM
	vkool_jxs_city 
WHERE
	id NOT IN ( SELECT c1.id FROM vkool_jxs_city c1, vkool_jxs_city_copy1 c2 WHERE c1.id = c2.id );
 
 # delete 要再套一层，不然会报错
 DELETE 
FROM
	vkool_jxs 
WHERE
	id NOT IN ( SELECT * FROM ( SELECT max( j.id ) FROM vkool_jxs j GROUP BY j.jxs_name, j.jxs_type ) x );