最近处理的系统中出现了大量重复数据，身份证号和姓名一样。而身份证号是作为用户登录系统的用户名，这样如果用户修改了密码，就有可能出现登录不了的情况。
参阅了相关资料后，找到一种比较方便的删除重复数据的方法，记录如下（方便以后参考）：
1
delete
from
t_test
where
rowid
not
in
2 ( select max (t.rowid) from t_test t group by name,cardid);
2 ( select max (t.rowid) from t_test t group by name,cardid);
备份其它的语句:
根据身份证号码更新用户的的性别信息：
update users set gender='男' where length(idcard)=18 and substr(idcard, 17, 1) in ('1','3','5','7','9')
update users set gender='女' where length(idcard)=18 and substr(idcard, 17, 1) in ('0','2','4','6','8')
update users set gender='男' where length(idcard)=15 and substr(idcard, 15, 1) in ('1','3','5','7','9')
update users set gender='女' where length(idcard)=15 and substr(idcard, 15, 1) in ('0','2','4','6','8')
select t.idcard, t.gender from users t
更新人员的身份证号码信息：
update
t_mytable
set
cardid
=
substr(cardid,
0
,
17
)
||
'
X
'
where
cardid
like
'
%x
'
and
cardtype
=
'
居民身份证
'
and
length(cardid)
=
18
使用A表的数据更新B表的对应数据：
update
t_e1
set
(inyear)
=
(
select
exyear
as
inyear
from t_tempyear where t_e1.eneeid = t_tempyear.eneeid)
where exists ( select 1 from t_tempyear where t_tempyear.eneeid = t_e1.eneeid)
from t_tempyear where t_e1.eneeid = t_tempyear.eneeid)
where exists ( select 1 from t_tempyear where t_tempyear.eneeid = t_e1.eneeid)
转载于:https://my.oschina.net/usenrong/blog/197815