1日期函數

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mysql> select current_date() from dual;

mysql> select current_time() from dual;

mysql> select month(current_date()) from dual;

mysql> select year(current_date()) from dual;

mysql> select month(current_date()) from dual;

mysql> select day(current_date()) from dual;

mysql> select hour(current_time()) from dual;

mysql> select minute(current_time()) from dual;

mysql> select second(current_time()) from dual;

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create table message (

id int,

title varchar(64),

publishdate datetime

);

mysql> insert into message (id,title,publishdate)values(1,'abc',now());

Query OK, 1 row affected (0.09 sec)

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mysql> insert into message (id,title,publishdate)values(1,'efc','2011-1-1');

Query OK, 1 row affected (0.09 sec)

備注：插入時間的內容可以是字符串，但是必須是日期格式

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查詢最近兩個小時的內容

select * from message where date_add(publishdate,interval 2 hour)>= now();

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選擇了最近的 30天內所有帶有date_col 值的記錄：?

mysql> SELECT something FROM tbl_name

? ? -> WHERE DATE_SUB(CURDATE(),INTERVAL 30 DAY) <= date_col;

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函數調用格式

DATE_ADD(date, INTERVAL expr type )?

DATE_SUB(date, INTERVAL expr type )?

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type 值	預期的 expr 格式
MICROSECOND	MICROSECONDS
SECOND	SECONDS
MINUTE	MINUTES
HOUR	HOURS
DAY	DAYS
WEEK	WEEKS
MONTH	MONTHS
QUARTER	QUARTERS
YEAR	YEARS

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2字符串函數

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mysql> select * from employee;

+------+------+------+------------+--------+------------+------------+

| id ? | name | sex ?| birthday ? | salary | entry_date | resume ? ? |

+------+------+------+------------+--------+------------+------------+

| ? ?1 | aaa ?| ? ? ?| 1977-11-11 | ? 56.8 | 2014-11-10 | hello word |

| ? ?2 | bbb ?| ? ? ?| 1977-11-11 | ? 57.8 | 2014-11-10 | hello word |

| ? ?3 | ccc ?| ? ? ?| 1977-11-11 | ? 56.3 | 2014-11-10 | hello word |

+------+------+------+------------+--------+------------+------------+

1rows in set (0.00 sec)

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名字首字母大寫

select SUBSTRING(UCASE(name),1,1) from employee;

select SUBSTRING(LCASE(name),2,LENGTH(name)-1) from employee;

select CONCAT(SUBSTRING(UCASE(name),1,1), SUBSTRING(LCASE(name),2,LENGTH(name)-1)) from employee;

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備注：SUBSTRING從第一個數從0開始

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3數學函數

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4加密函數

4.1md5加密

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mysql> select md5('huangbiao') from dual;

+----------------------------------+

| md5('huangbiao') ? ? ? ? ? ? ? ? |

+----------------------------------+

| 1d7877a910293815774015e3776afa0c |

+----------------------------------+

1 row in set (0.00 sec)

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mysql> select md5('huangbiao') ;

+----------------------------------+

| md5('huangbiao') ? ? ? ? ? ? ? ? |

+----------------------------------+

| 1d7877a910293815774015e3776afa0c |

+----------------------------------+

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4.2password(str)

從原文密碼str 計算并返回密碼字符串，當參數為 NULL 時返回 NULL。這個函數用于用戶授權表的Password列中的加密MySQL密碼存儲

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mysql> select password('1');

+-------------------------------------------+

| password('1') ? ? ? ? ? ? ? ? ? ? ? ? ? ? |

+-------------------------------------------+

| *E6CC90B878B948C35E92B003C792C46C58C4AF40 |

+-------------------------------------------+?

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mysql> select password(NULL);

+----------------+

| password(NULL) |

+----------------+

| NULL ? ? ? ? ? |

+----------------+

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4.3SHA1(str) SHA(str)?

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mysql> SELECT SHA1('1');

+------------------------------------------+

| SHA1('1') ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|

+------------------------------------------+

| 356a192b7913b04c54574d18c28d46e6395428ab |

+------------------------------------------+

1 row in set (0.00 sec)

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mysql> SELECT SHA('1');

+------------------------------------------+

| SHA('1') ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |

+------------------------------------------+

| 356a192b7913b04c54574d18c28d46e6395428ab |

+------------------------------------------+

1 row in set (0.00 sec)

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4.4DECODE(crypt_str,pass_str) ?和 ENCODE(str,pass_str)

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使用 pass_str 作為密碼，解密加密字符串 crypt_str， crypt_str 應該是由ENCODE()返回的字符串。?

使用pass_str 作為密碼，解密 str 。 使用DECODE()解密結果

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