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[数据库]《与mysql零距离接触》视屏学习笔记


1、数据表的增删改查操作(crud):

对于表:

      增:create  table  XXXX

      删:drop table XXXX

      改:alter table XXXX rename to XXXX

      查:select * from XXXX

对于行:

      增:insert  into  XXXX(xxxx) values (xxxx)

               insert into XXXX set xxxx=xx , xxxx=xx

      删:delete from XXXX where xxxx

      改:update table set xxxx=xxxx where xxxx=xxxx

      查:select xxxx from XXXX

 对于列:

      增:alter  table  XXXX add xxxx()

      删:alter table XXXX drop xxxx

      改:alter table XXXX change xxxx xxxx xxxx

               alter table XXXX modify xxxx xxxx

      查:show columns from XXXX

 

2、运算符与函数

字符函数

Concat()                  select concat('hha','-','hdf')

Concat_ws()           select concat_ws('=','A','B','C')

Format()                  select format(125060.752,2)

Lower()                    select lower('HIIHO')

Upper()                    select upper('fsfds')

Left()                        select left('fsfds',2)

Right()                      select right('fsfds',2)

Length()                   select length(' fsfds ')

Ltrim()                      select ltrim(' fsfds ')

Rtrim()                     select rtrim(' fsfds ')

Trim()                       select trim(' fsfds ')

                                  select trim(leading '?' from ' fs?fds ')

                                  select trim(trailing '?' from ' fs?fds ')

                                  select trim(both '?' from ' fs?fds ')

Substring()              select substring(' fsfds ',2,3)

                                  select substring(' fsfds ',2)

Like                           select 'myufsd' like 'm%'

                                  select * from test where first_name like '%1%%' escape '1'

                                  %代表任意个字符

                                   _代表任意一个字符

Replace()                 select replace('fsgasgsfa','s','t')

 

3、数值运算符

Div                             整数除法

 

4、比较运算符合函数

Not  between   and

Not  in

 

5、时间和日期函数

Now()

Curdate()

Curtime()

Date_add()

Datediff()

Date_format()

 

6、信息函数

Connection_id()

Datebase()

Last_insert_id()

User()

Version()

 

7聚合函数

。。。

 

8、加密函数

Md5()

Password()