1. <=>安全等于 用于比较null 两者同为null时才为1 否则0
2.regexp或rlike 正则表达式匹配
3.not或！逻辑非 and或&& 逻辑与 or或|| 逻辑或 xor 逻辑异或
4.&按位与 |按位或 <<按位左移 >>按位右移
5.char_length(str)或CHARACTER_LENGTH(str) 计算字符长度 大小写长度一样
6.concat('zhang', 'sna') zhangsna concat_ws(',', 'zhang', 'sna') zhang,sna 字符串连接
7.SELECT FIELD(null, "a", "b", "c", "d", "e") 0 返回第一个字符串在后续字符串列表中的位置 0为没找到 从1开始 不区分大小写
8.select FIND_IN_SET('ed', 'a……b_cd,ed') 2 返回第一个字符串在字符串列表中的位置索引 mysql只能识别，分隔符 不区分大小写
9.select format(234.456, 7) 234.4560000 select format(234.456, 2) 234.46 四舍五入 select truncate(234.456, 2) 234.45 不会四舍五入
10.insert('baidu.com', 2, 5, 'google') bgooglecom
11.select LOCATE('LR', 'oorlrrpa')或select position('lr' in 'oorlrrpa') 4 不区分大小写
12.lower(str)或lcase(str) ucase(str)或upper(str) ltrim 去做空格 rtrim 去有空格 trim 去左右空格
13.select lpad('abc', 8, 'r g') r gr abc select rpad('abc', 8, 'r g') abcr gr 左右填充
14.repeat('10', 10) 10101010101010101010 space(10) 10个空格
15.REVERSE('zhangsan') nasgnahz
16.select strcmp('ach', 'tbo') 字符串比较大小 从第一个字母的ascii编码开始
17.left('avedefg', 2) av select right('avedefg', 3) efg select mid('avedefg', 2, 3)或select substr('avedefg', 2, 3)或select substring('avedefg', 2, 3) ved
substring_index('a*b*c*d*e','*',3) a*b*c SUBSTRING_INDEX('a*b*c','*',-1) c 字符串截取
18.select REPLACE('avedafg', 'a', 'pp') ppvedppfg select REPLACE('avedafg', 't', 'pp') avedafg 字符串替换 找不到则不会替换
19.ceil(x)或ceiling(x) 返回大于或等于x的最小整数 floor(x) 返回小于或等于x的最大整数 round(3.5)=4 返回离 x 最近的整数 exp(3) e的三次方 pow(3, 2)或power(3, 2)=9 3的2次方 pi()=3.141593 圆周率 sqrt(25)=5 rand() 0-1随机数
20. least(5, 6) 5 greatest(5, 6) 6
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日期函数
SELECT NOW() 2021-01-12 15:29:11
SELECT SYSDATE() 2021-01-12 15:44:45
SELECT CURDATE(); 2021-01-12
SELECT CURRENT_DATE(); 2021-01-12
SELECT CURTIME(); 15:25:39
SELECT CURRENT_TIME(); 15:24:59
SELECT LOCALTIME() 2021-01-12 15:25:12
SELECT LOCALTIMESTAMP() 2021-01-12 15:24:53
SELECT CURRENT_TIMESTAMP() 2021-01-12 15:24:48
SELECT MAKEDATE(2017, 3); 2017-01-03
SELECT MAKETIME(11, 35, 4); 11:35:04
SELECT FROM_DAYS(365) x > 365 x <= 365 0000-00-00 x必须大于等于366
SELECT DATE("2017-06-15"); 2017-06-15
SELECT TIME("19:30:10"); 19:30:10
SELECT TIMESTAMP("2017-07-23", "13:10:11"); 2017-07-23 13:10:11
SELECT TIMESTAMP("2017-07-23"); 2017-07-23 00:00:00
SELECT SEC_TO_TIME(4320) 01:12:00
SELECT TIME_TO_SEC('1:12:00') 4320
SELECT STR_TO_DATE("August 10 2017", "%M %d %Y"); 2017-08-10
SELECT STR_TO_DATE("2017-10-August", "%Y-%d-%M"); 2017-08-10
SELECT TO_DAYS('0001-01-01 01:01:01') 366
SELECT LAST_DAY("2017-06-20"); 2017-06-30 指定日期所属月份最后一天
SELECT PERIOD_ADD(201703, 5); 201708 不能加分隔符
SELECT PERIOD_DIFF(201703, 201710); 7 前-后
SELECT DATEDIFF('2001-01-01','2001-01-03')
SELECT TIMEDIFF("13:10:11", "13:10:12"); -00:00:01 前-后
SELECT ADDDATE('2011-11-11 11:11:11',1)
SELECT DATE_ADD('2011-11-11 11:11:11', INTERVAL 1 year) 时间日期可加
SELECT DATE_FORMAT('2011-11-11 14:11:11','%Y-%m-%d %h-%i-%s') 2011-11-11 02-11-11
SELECT DATE_FORMAT('2011-11-11','%Y-%m-%d %h-%i-%s') 2011-11-11 12-00-00 默认输出12点
SELECT DATE_FORMAT('2011-11-11 14:11:11','%Y-%m-%d %H-%i-%s') 2011-11-11 14-11-11
SELECT DATE_FORMAT('2011-11-11 14:11:11','%Y-%m-%d %T') 2011-11-11 14:11:11
SELECT DATE_FORMAT('2011-11-11 14:11:11','%Y-%m-%d %r') 2011-11-11 02:11:11 PM
SELECT TIME_FORMAT('11:11:11','%r')
SELECT TIME_FORMAT('11:11:11','%T')
SELECT DATE_SUB('2011-11-11 14:11:11', INTERVAL 1 hour) 2011-11-11 13:11:11
SELECT SUBDATE('2011-11-11 11:11:11', 1) 2011-11-10 11:11:11
SELECT SUBTIME('2011-11-11 11:11:11', 5) 2011-11-11 11:11:06
SELECT DAY("2017/06_5"); 5
SELECT HOUR('1:2:3')
SELECT SECOND('1:2:3')
SELECT MINUTE('1:02:3') 2
SELECT YEAR("2017-06-15"); 2017
SELECT YEARWEEK("2017-06-15"); 201724
SELECT MONTH('2011-10-12 13:14:15.456') 10
SELECT WEEK('2011-11-11 11:11:11') 45
SELECT WEEKDAY("2017-06-15"); 3
SELECT WEEKOFYEAR('2011-11-11 11:11:11') 45
SELECT DAYNAME('2011-11-11 11:11:11') Friday
SELECT DAYOFMONTH('2011-11-11 11:11:11') 11
SELECT DAYOFWEEK('2011-11-11 11:11:11') 6
SELECT DAYOFYEAR('2011-11-11 11:11:11') 315
SELECT MONTHNAME('2011-11-11 11:11:11') November
SELECT MICROSECOND("2017-06-20 09:34:00.000023"); 23
SELECT QUARTER('2011-11-11 11:11:11') 4
SELECT EXTRACT(HOUR FROM '2011-11-12 13:14:15.456')
SELECT NOW() 2021-01-12 15:29:11
SELECT SYSDATE() 2021-01-12 15:44:45
SELECT CURDATE(); 2021-01-12
SELECT CURRENT_DATE(); 2021-01-12
SELECT CURTIME(); 15:25:39
SELECT CURRENT_TIME(); 15:24:59
SELECT LOCALTIME() 2021-01-12 15:25:12
SELECT LOCALTIMESTAMP() 2021-01-12 15:24:53
SELECT CURRENT_TIMESTAMP() 2021-01-12 15:24:48
SELECT MAKEDATE(2017, 3); 2017-01-03
SELECT MAKETIME(11, 35, 4); 11:35:04
SELECT FROM_DAYS(365) x > 365 x <= 365 0000-00-00 x必须大于等于366
SELECT DATE("2017-06-15"); 2017-06-15
SELECT TIME("19:30:10"); 19:30:10
SELECT TIMESTAMP("2017-07-23", "13:10:11"); 2017-07-23 13:10:11
SELECT TIMESTAMP("2017-07-23"); 2017-07-23 00:00:00
SELECT SEC_TO_TIME(4320) 01:12:00
SELECT TIME_TO_SEC('1:12:00') 4320
SELECT STR_TO_DATE("August 10 2017", "%M %d %Y"); 2017-08-10
SELECT STR_TO_DATE("2017-10-August", "%Y-%d-%M"); 2017-08-10
SELECT TO_DAYS('0001-01-01 01:01:01') 366
SELECT LAST_DAY("2017-06-20"); 2017-06-30 指定日期所属月份最后一天
SELECT PERIOD_ADD(201703, 5); 201708 不能加分隔符
SELECT PERIOD_DIFF(201703, 201710); 7 前-后
SELECT DATEDIFF('2001-01-01','2001-01-03')
SELECT TIMEDIFF("13:10:11", "13:10:12"); -00:00:01 前-后
SELECT ADDDATE('2011-11-11 11:11:11',1)
SELECT DATE_ADD('2011-11-11 11:11:11', INTERVAL 1 year) 时间日期可加
SELECT DATE_FORMAT('2011-11-11 14:11:11','%Y-%m-%d %h-%i-%s') 2011-11-11 02-11-11
SELECT DATE_FORMAT('2011-11-11','%Y-%m-%d %h-%i-%s') 2011-11-11 12-00-00 默认输出12点
SELECT DATE_FORMAT('2011-11-11 14:11:11','%Y-%m-%d %H-%i-%s') 2011-11-11 14-11-11
SELECT DATE_FORMAT('2011-11-11 14:11:11','%Y-%m-%d %T') 2011-11-11 14:11:11
SELECT DATE_FORMAT('2011-11-11 14:11:11','%Y-%m-%d %r') 2011-11-11 02:11:11 PM
SELECT TIME_FORMAT('11:11:11','%r')
SELECT TIME_FORMAT('11:11:11','%T')
SELECT DATE_SUB('2011-11-11 14:11:11', INTERVAL 1 hour) 2011-11-11 13:11:11
SELECT SUBDATE('2011-11-11 11:11:11', 1) 2011-11-10 11:11:11
SELECT SUBTIME('2011-11-11 11:11:11', 5) 2011-11-11 11:11:06
SELECT DAY("2017/06_5"); 5
SELECT HOUR('1:2:3')
SELECT SECOND('1:2:3')
SELECT MINUTE('1:02:3') 2
SELECT YEAR("2017-06-15"); 2017
SELECT YEARWEEK("2017-06-15"); 201724
SELECT MONTH('2011-10-12 13:14:15.456') 10
SELECT WEEK('2011-11-11 11:11:11') 45
SELECT WEEKDAY("2017-06-15"); 3
SELECT WEEKOFYEAR('2011-11-11 11:11:11') 45
SELECT DAYNAME('2011-11-11 11:11:11') Friday
SELECT DAYOFMONTH('2011-11-11 11:11:11') 11
SELECT DAYOFWEEK('2011-11-11 11:11:11') 6
SELECT DAYOFYEAR('2011-11-11 11:11:11') 315
SELECT MONTHNAME('2011-11-11 11:11:11') November
SELECT MICROSECOND("2017-06-20 09:34:00.000023"); 23
SELECT QUARTER('2011-11-11 11:11:11') 4
SELECT EXTRACT(HOUR FROM '2011-11-12 13:14:15.456')
可选参数
- MICROSECOND
- SECOND
- MINUTE
- HOUR
- DAY
- WEEK
- MONTH
- QUARTER
- YEAR
- SECOND_MICROSECOND
- MINUTE_MICROSECOND
- MINUTE_SECOND
- HOUR_MICROSECOND
- HOUR_SECOND
- HOUR_MINUTE
- DAY_MICROSECOND
- DAY_SECOND
- DAY_MINUTE
- DAY_HOUR
- YEAR_MONTH
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高级函数
SELECT bin(x) 返回x的二进制编码
SELECT BINARY 'dfiro' = 'DFIRO' 0
SELECT 'dfiro' = 'DFIRO' 1
select case when user_level=1 then '1' when user_level=2 then '2' else '3' end from tb_user
select case user_level when 1 then '1' when 2 then '2' else '3' end from tb_user
SELECT CAST("2017-08-29" AS DATE); 数据类型转换
SELECT COALESCE(NULL, '', ' 1', 'runoob.com', NULL, 'google.com'); 返回第一个非null的表达式值
SELECT CAST("2017-08-29" AS DATE); 数据类型转换
SELECT COALESCE(NULL, '', ' 1', 'runoob.com', NULL, 'google.com');
SELECT CONV(15, 10, 2); 15转化为二进制数
SELECT CHARSET('ABC') utf8mb4
SELECT CHARSET(CONVERT('ABC' USING gbk)) gbk
select user() 用户名@ip
select SYSTEM_USER() 用户名@本地ip
select version()
select CURRENT_USER() 用户名@%
select SESSION_USER() 用户名@ip
select DATABASE()
select isnull('') 0
select isnull(null) 1
select if(1=1, 2, 3) 2
select IFNULL(null, 2) 第一个不为null返回第一个 否则返回第二个
select NULLIF('ab','AB1') 两字符串相等(不区分大小写)返回NULL 否则返回第一个字符串