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count()
SELECT (SELECT count(1) FROM ecs_category) as 'Export category count', (SELECT count(1) FROM ecs_goods) as 'Goods count', (SELECT count(1) FROM ecs_goods_attr) as 'Attr count';
LEFT(str,len)
mysql> select left(concat('1','0000000'),5) as number;
+--------+
| number |
+--------+
| 10000 |
+--------+
1 row in set (0.00 sec)
RIGHT(str,len)
mysql> select right(concat('0000000','1'),5) as number;
+--------+
| number |
+--------+
| 00001 |
+--------+
1 row in set (0.00 sec)
補齊長度用'0'填充
RPAD(str,len,padstr)
mysql> select rpad('10',5,'0') as txt;
+-------+
| txt |
+-------+
| 10000 |
+-------+
1 row in set (0.01 sec)
LPAD(str,len,padstr)
mysql> select lpad('10',5,'0') as txt;
+-------+
| txt |
+-------+
| 00010 |
+-------+
1 row in set (0.00 sec)
CONCAT(str1,str2,...)
mysql> select concat('Neo',' ','Chen') as Name;
+----------+
| Name |
+----------+
| Neo Chen |
+----------+
1 row in set (0.00 sec)
mysql> select GROUP_CONCAT(CONVERT( username , CHAR (16)) order by username desc) as username from test; +-------------------------------------------+ | username | +-------------------------------------------+ | jam,jam2,john,john2,john3,neo,neo1,neo2 | +-------------------------------------------+ 6 rows in set, 1 warning (0.01 sec)
mysql> select year('2012-03-20');
+--------------------+
| year('2012-03-20') |
+--------------------+
| 2012 |
+--------------------+
1 row in set (0.00 sec)
mysql> select month('2012-03-20');
+---------------------+
| month('2012-03-20') |
+---------------------+
| 3 |
+---------------------+
1 row in set (0.00 sec)
mysql> select day('2012-03-20');
+-------------------+
| day('2012-03-20') |
+-------------------+
| 20 |
+-------------------+
1 row in set (0.00 sec)
mysql> select hour('12:30:55');
+------------------+
| hour('12:30:55') |
+------------------+
| 12 |
+------------------+
1 row in set (0.00 sec)
mysql> select minute('12:30:55');
+--------------------+
| minute('12:30:55') |
+--------------------+
| 30 |
+--------------------+
1 row in set (0.00 sec)
mysql> select second('12:30:55');
+--------------------+
| second('12:30:55') |
+--------------------+
| 55 |
+--------------------+
1 row in set (0.00 sec)
mysql> SELECT UNIX_TIMESTAMP('2005-03-27 02:00:00');
+---------------------------------------+
| UNIX_TIMESTAMP('2005-03-27 02:00:00') |
+---------------------------------------+
| 1111885200 |
+---------------------------------------+
mysql> SELECT FROM_UNIXTIME(1111885200);
+---------------------------+
| FROM_UNIXTIME(1111885200) |
+---------------------------+
| 2005-03-27 03:00:00 |
+---------------------------+
SELECT UNIX_TIMESTAMP('2012-01-01 00:00:00');
SELECT UNIX_TIMESTAMP('2012-07-30 00:00:00');
SELECT UNIX_TIMESTAMP();
SELECT UNIX_TIMESTAMP('2009-08-06') ;
SELECT UNIX_TIMESTAMP( curdate( ) );
select FROM_UNIXTIME(UNIX_TIMESTAMP('2012-07-30 00:00:00'), '%Y-%m-%d');
SELECT FROM_UNIXTIME( 1249488000, '%Y年%m月%d日' );
select FROM_UNIXTIME(createtime, '%m') as month, count(1) as count from members where createtime BETWEEN UNIX_TIMESTAMP('2012-01-01 00:00:00') and UNIX_TIMESTAMP('2012-12-31 00:00:00') group by FROM_UNIXTIME(createtime, '%m');
select FROM_UNIXTIME(createtime, '%m') as month, count(1) as count from members where createtime BETWEEN UNIX_TIMESTAMP('2011-01-01 00:00:00') and UNIX_TIMESTAMP('2011-12-31 00:00:00') group by FROM_UNIXTIME(createtime, '%m');
select FROM_UNIXTIME(createtime, '%m-%d') as month, count(1) as count from members where createtime BETWEEN UNIX_TIMESTAMP('2011-01-01 00:00:00') and UNIX_TIMESTAMP('2011-12-31 00:00:00') group by FROM_UNIXTIME(createtime, '%m-%d');
select FROM_UNIXTIME(createtime, '%m-%d') as month, count(1) as count from members where createtime BETWEEN UNIX_TIMESTAMP('2012-01-01 00:00:00') and UNIX_TIMESTAMP('2012-12-31 00:00:00') group by FROM_UNIXTIME(createtime, '%m-%d');
DATE_FORMAT() 函數用於以不同的格式顯示日期/時間數據。
語法 DATE_FORMAT(date,format) date 參數是合法的日期。format 規定日期/時間的輸出格式。 可以使用的格式有： 格式 描述 %a 縮寫星期名 %b 縮寫月名 %c 月，數值 %D 帶有英文首碼的月中的天 %d 月的天，數值(00-31) %e 月的天，數值(0-31) %f 微秒 %H 小時 (00-23) %h 小時 (01-12) %I 小時 (01-12) %i 分鐘，數值(00-59) %j 年的天 (001-366) %k 小時 (0-23) %l 小時 (1-12) %M 月名 %m 月，數值(00-12) %p AM 或 PM %r 時間，12-小時（hh:mm:ss AM 或 PM） %S 秒(00-59) %s 秒(00-59) %T 時間, 24-小時 (hh:mm:ss) %U 周 (00-53) 星期日是一周的第一天 %u 周 (00-53) 星期一是一周的第一天 %V 周 (01-53) 星期日是一周的第一天，與 %X 使用 %v 周 (01-53) 星期一是一周的第一天，與 %x 使用 %W 星期名 %w 周的天 （0=星期日, 6=星期六） %X 年，其中的星期日是周的第一天，4 位，與 %V 使用 %x 年，其中的星期一是周的第一天，4 位，與 %v 使用 %Y 年，4 位 %y 年，2 位
實例
下面的腳本使用 DATE_FORMAT() 函數來顯示不同的格式。我們使用 NOW() 來獲得當前的日期/時間： DATE_FORMAT(NOW(),'%b %d %Y %h:%i %p') DATE_FORMAT(NOW(),'%m-%d-%Y') DATE_FORMAT(NOW(),'%d %b %y') DATE_FORMAT(NOW(),'%d %b %Y %T:%f') SELECT DATE_FORMAT(NOW(),'%Y-%m-%d'); select DATE_FORMAT(asctime,'%Y-%m-%d') as Date, count(1) as Count from logging where tag='www' and facility='login' group by DATE_FORMAT(asctime,'%Y-%m-%d') order by asctime desc;
當前時間向後推10天
mysql> select DATE_SUB(now(), INTERVAL 240 HOUR); +------------------------------------+ | DATE_SUB(now(), INTERVAL 240 HOUR) | +------------------------------------+ | 2012-03-09 10:26:03 | +------------------------------------+ 1 row in set (0.00 sec) mysql> select DATE_SUB(now(), INTERVAL 24 HOUR); +-----------------------------------+ | DATE_SUB(now(), INTERVAL 24 HOUR) | +-----------------------------------+ | 2012-03-18 10:28:43 | +-----------------------------------+ 1 row in set (0.00 sec)
DELETE from Message where created < DATE_sub(now(), INTERVAL 240 HOUR);
計算時間差，兩個時間相減結果
mysql> select timediff('22:20:00','17:30:00');
+---------------------------------+
| timediff('22:20:00','17:30:00') |
+---------------------------------+
| 04:50:00 |
+---------------------------------+
1 row in set (0.00 sec)
mysql> select datediff('2008-08-08 12:00:00', '2008-08-01 00:00:00');
+--------------------------------------------------------+
| datediff('2008-08-08 12:00:00', '2008-08-01 00:00:00') |
+--------------------------------------------------------+
| 7 |
+--------------------------------------------------------+
1 row in set (0.00 sec)