||
https://blog.csdn.net/yuqiongran/article/details/52571857
MySQL 字符串截取函数
https://blog.csdn.net/mycms5/article/details/52725877
MySQL日期和字符串转换函数实例
https://www.2cto.com/database/201805/743743.html
https://blog.csdn.net/superit401/article/details/53929443
https://www.cnblogs.com/laozhanghahaha/p/6907069.html
SQLServer SQL语句格式化日期时间年月日时分秒,去掉毫秒
https://blog.csdn.net/chinaplan/article/details/80469638
mysql日期加减
https://www.cnblogs.com/winner-0715/p/6132838.html
select curdate(),now(),date(now());
mysql 获取当前日期周一和周日
https://blog.csdn.net/huanghanqian/article/details/53540392
select subdate(curdate(),date_format(curdate(),'%w')-1)//获取当前日期在本周的周一
select subdate(curdate(),date_format(curdate(),'%w')-2)//获取当前日期在本周的周二
select subdate(curdate(),date_format(curdate(),'%w')-7)//获取当前日期在本周的周日
%W 星期名字(Sunday……Saturday)
%w 一个星期中的天数(0=Sunday ……6=Saturday )
mysql日期 获取本月第一天 获取下个月的第一天
https://www.cnblogs.com/wujf/p/9364878.html
mysql加减时间-函数-时间加减
https://blog.csdn.net/yuxiayiji/article/details/7480785
select dayofweek(now());
select DAYNAME('2019-03-02');##周六1,周日7
MySQL时间戳和时间的获取/相互转换/格式化
https://blog.csdn.net/lilongsy/article/details/79061639
sql点滴—mysql中查询表的信息
https://www.cnblogs.com/tylerdonet/p/5509398.html
https://blog.csdn.net/wolangjushi/article/details/19966563
https://blog.csdn.net/wangzaza/article/details/79484069
https://blog.csdn.net/wangzaza/article/details/79484069
MySQL ERROR 1799 (HY000) innodb_online_alter_log_max_size参数过小的一则case
https://www.linuxidc.com/Linux/2017-06/145042.htm
解决MySql查询语句报Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggre异常的问题
https://blog.csdn.net/fansili/article/details/78664267
https://blog.csdn.net/qq_34246315/article/details/81584343
mongo的安装和运行
https://blog.csdn.net/qq_39729527/article/details/81285072
MongoDB Shell和Robo3T使用以及与SQL语法比较
https://blog.csdn.net/freeking101/article/details/80795412
MongoDB常用操作命令大全
https://blog.csdn.net/piaocoder/article/details/52384756
robomongo(robo3T)操作MongoDB数据库常用命令
https://blog.csdn.net/qq_27378621/article/details/80006734
mongodb报错1: connecting to:mongodb://127.0.0.1:27017. connect failed
https://blog.csdn.net/qq_39729527/article/details/81285405?utm_source=blogxgwz0
Mongodb连接失败问题的几种情况和解决方式
https://blog.csdn.net/u011642782/article/details/79193188
11/19/2014 13:37:51 格式转换 2014-11-19
变换日期的分割符
UPDATE tab_a_time_copy1 SET `下单时间`=REPLACE(`下单时间`,'/','-')
将时间去除
方法1
update tab_a_time_delimiter_copy1
set `下单时间`=replace(`下单时间`,substring(`下单时间`,-9,9),'')
方法2
update tab_a_time_delimiter_copy1
set `下单时间`= substring_index(`下单时间`, ' ', 1);
#UPDATE tab_a_time_copy1 Set `下单时间`=REPLACE(`下单时间`,'/','-')
update tab_a_time_copy1
set `下单时间`=replace(`下单时间`,substring(`下单时间`,-9,9),'')
#set `下单时间`=replace(`下单时间`,substring(`下单时间`,-9,9),'')
#substring(str, pos, length)
#select substring_index('3-28-2017 14:52:19', ' ', 1);
#select str_to_date(‘2014-04-22 15:47:06’,’%Y-%m-%d %H:%i:%s’)
在前面加上-
update tab_a_time_delimiter_copy1
set `下单时间`=replace(`下单时间`,substring(`下单时间`,1,1),concat('-',substring(`下单时间`,1,1)))
年份放在最前面
update tab_a_time_delimiter_copy1
set `下单时间`=replace(`下单时间`,substring(`下单时间`, 1),concat(substring(`下单时间`,-4,4),substring(`下单时间`, 1)))
去除后面的年份
update tab_a_time_delimiter_copy1
set `下单时间`=replace(`下单时间`,substring(`下单时间`,-5,5),'')
补齐单位数月份前面的0
update tab_a_time_delimiter_copy1_copy1
set
`下单时间`=replace(`下单时间`,substring(`下单时间`, 1, 5),concat(substring(`下单时间`,1,5),'0')) WHERE `下单时间` LIKE '%-_-%'
select * from tab_a_time_delimiter_copy1_copy1 WHERE `下单时间` LIKE '%-_-%'
补齐单位数日子前面的0
update tab_a_time_delimiter_copy1_copy1
set
`下单时间`=replace(`下单时间`,substring(`下单时间`, 1, 8),concat(substring(`下单时间`,1,8),'0')) WHERE `下单时间` LIKE '%-_'
select * from tab_a_time_delimiter_copy1_copy1 WHERE `下单时间` LIKE '%-_'
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