业务:一个表中有很多数据(id为自增主键),在这些数据中有个别数据出现了重复的数据. 目标:需要把这些重复数据删除同时保留第一次插入的那一条数据,还要保持其它的数据不受影响. 解题过程: 第一步:查出所有要保留的下来的数据的id(save_id) SELECT id as save_id FROM yujing.alarm_event_info_snapshot aeis where aeis.event_id in (SELECT ae.id FROM yujing.alarm_event a
表结构: LOAD DATA INFILE '/usr/local/phone_imsi_12' replace INTO TABLE tbl_imsi2number_new FIELDS TERMINATED BY '\t' ENCLOSED BY '' (number,imsi); 先用SQL语句来进行去重操作: delete from tbl_imsi2number_new where imsi in (select imsi from (select imsi from tbl_imsi
添加表的字段 alter table 表名 add 字段名 字段的类型 例子: alter table table1 add transactor varchar(10) not Null; alter table table1 add id int unsigned not Null auto_increment primary key 在mysql数据库中怎样在指定的一个字段后面添加一个字段: alter table newexample add address
<!-- 根据主键批量删除 --> <delete id="deleteByKeys"> DELETE FROM product WHERE id in <foreach collection="list" separator="," item="id" open="(" close=")"> #{id} </foreach> </d