返回日期相关的
Now() || CURRENT_TIMESTAMP();返回当前时间
to_days(date) 返回日期date是西元0年至今多少天(不计算1582年以前) 转换为天数 date是日期类型
FROM_DAYS(N) 给出西元0年至今多少天返回DATE值(不计算1582年以前)
CURDATE()||CURRENT_DATE()||SYSDATE() 当前日期 //注意大写
weekDay(date) 返回指定日期的星期几 //参数是日期型,不能是时间戳格式
DAYOFWEEK(date) 返回指定日期的星期几 //参数是日期型,不能是时间戳格式
DAYNAME(date) 返回指定日期的星期几,具体到英文单词 //参数是日期型,不能是时间戳格式
WEEK(date,first)//参数是日期型,不能是时间戳格式 返回date是一年的第几周(first默认值0,first取值1表示周一是周的开始,0从周日开始)
DAYOFMONTH(date) 返回指定日期是当月的几号 //参数是日期型,不能是时间戳格式
MONTH(date) 返回指定日期的月份 //参数是日期型,不能是时间戳格式
MONTHNAME 返回date是几月(按英文名返回)//参数是日期型,不能是时间戳格式
QUARTER(date) 返回date是一年的第几个季度 //参数是日期型,不能是时间戳格式
YEAR(date) 返回date年份 //参数是日期型,不能是时间戳格式
DATE_FORMAT(Date,format);根据format字符串格式化date值
select DATE_FORMAT(CURDATE(),'%W %M %Y');
%W 代表英文归属星期几
%M 代表英文归属月份
%Y 代表英文归属年份
select DATE_FORMAT(Now(),'%H:%i:%s');
%H 返回小时数
%i 返回分钟数
%s 返回秒数
select DATE_FORMAT(Now(),'%D %y %a %d %m %b %j')
%j 一年中的天数(001……366)
%b 缩写的月份名字(Jan……Dec)
%m 月, 数字(01……12)
%d 月份中的天数, 数字(00……31)
%a 缩写的星期名字(Sun……Sat)
%y 年, 数字, 2 位
%D 有英语前缀的月份的日期(1st, 2nd, 3rd, 等等。)
select DATE_FORMAT(Now(),'%H %k %I %r %T %S %w');
%k 小时(0……23)
%l 小时(1……12)
%r 时间,12 小时(hh:mm:ss [AP]M)
%T 时间,24 小时(hh:mm:ss)
%S 秒(00……59)
%w 一个星期中的天数(0=Sunday ……6=Saturday )
%e 月份中的天数, 数字(0……31)
%b 缩写的月份名字(Jan……Dec)
%I 小时(01……12)
%s 秒(00……59)
%p AM或PM
%U 星期(0……52), 这里星期天是星期的第一天
%u 星期(0……52), 这里星期一是星期的第一天
%% 字符%
返回时间相关的
CURTIME() 返回当前时间
HOUR(); 返回小时数 //参数是日期型,不能是时间戳格式
MINUTE(time) 返回分钟数 //参数是日期型,不能是时间戳格式
SECOND(time) 返回秒数 //参数是日期型,不能是时间戳格式
日期的加减运算
DATE_ADD(date,INTERVAL expr type) 加法运算
DATE_SUB(date,INTERVAL expr type) 减法运算
ADDDATE(date,INTERVAL expr type) 加法
SUBDATE(date,INTERVAL expr type) 减法
对日期时间进行加减法运算
expr type 类型
SECOND 秒 SECONDS
MINUTE 分钟 MINUTES
HOUR 时间 HOURS
DAY 天 DAYS
MONTH 月 MONTHS
YEAR 年 YEARS
MINUTE_SECOND 分钟和秒 "MINUTES:SECONDS"
HOUR_MINUTE 小时和分钟 "HOURS:MINUTES"
DAY_HOUR 天和小时 "DAYS HOURS"
YEAR_MONTH 年和月 "YEARS-MONTHS"
HOUR_SECOND 小时, 分钟, "HOURS:MINUTES:SECONDS"
DAY_MINUTE 天, 小时, 分钟 "DAYS HOURS:MINUTES"
DAY_SECOND 天, 小时, 分钟, 秒 "DAYS HOURS:MINUTES:SECONDS"
SELECT ADDDATE(NOW(),INTERVAL 5 DAY);
SELECT DATE_ADD(NOW(),INTERVAL 5 DAY);
SELECT DATE_SUB(NOW(),INTERVAL 5 DAY);
SELECT SUBDATE(NOW(),INTERVAL 5 DAY);
UNIX_TIMESTAMP() UNIX_TIMESTAMP(Date ); 返回一个Unix时间戳(从'1970-01-01 00:00:00'GMT开始的秒数,就是秒数
FROM_UNIXTIME(UNIX_TIMESTAMP()) ; 根据这个秒数返回制定日期的字符串
FROM_UNIXTIME(unix_timestamp,format) 自己制定格式化,返回制定日期的字符串
TIME_TO_SEC(time) 返回time值有多少秒
SEC_TO_TIME(seconds) 以'HH:MM:SS'或HHMMSS格式返回秒数转成的TIME值(根据返回值所处上下文是字符串或数字)

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ToaddusersinMySQLeffectivelyandsecurely,followthesesteps:1)UsetheCREATEUSERstatementtoaddanewuser,specifyingthehostandastrongpassword.2)GrantnecessaryprivilegesusingtheGRANTstatement,adheringtotheprincipleofleastprivilege.3)Implementsecuritymeasuresl

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The best tools and technologies for automating the creation of users in MySQL include: 1. MySQLWorkbench, suitable for small to medium-sized environments, easy to use but high resource consumption; 2. Ansible, suitable for multi-server environments, simple but steep learning curve; 3. Custom Python scripts, flexible but need to ensure script security; 4. Puppet and Chef, suitable for large-scale environments, complex but scalable. Scale, learning curve and integration needs should be considered when choosing.

Yes,youcansearchinsideaBLOBinMySQLusingspecifictechniques.1)ConverttheBLOBtoaUTF-8stringwithCONVERTfunctionandsearchusingLIKE.2)ForcompressedBLOBs,useUNCOMPRESSbeforeconversion.3)Considerperformanceimpactsanddataencoding.4)Forcomplexdata,externalproc


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