Mobile Web Development tutorial Six, MySQL database basics

One, data type

1. Integral type

Data type storage space description range of values

TINYINT1 byte very small integer with symbolic value: -128~127

Unsigned value: 0~255

SMALLINT2 byte small integer with symbolic value: -32768~32767

Unsigned value: 0~65535

MEDIUMNT3 byte medium-sized integer with symbolic value: -8388608~8388607

Unsigned value: 0~16777215

INT4 byte standard integer with symbolic value: -2147483648~2147483647

Unsigned value: 0~4294967295

BIGINT8 byte Large integer

2, floating point type

Data type storage space description range of values

FLOAT4 bytes But precision floating-point numbers

DOUBLE8 byte double-precision floating-point number

The DECIMAL (m,d) customization is represented as a string

3. String type

Type storage space Description Maximum length

char[(m)]m byte fixed-length string M-byte

varchar[(m)]l+1 byte variable long string M byte

tinyblog,tingtextl+1 byte very small blob and text string 2^8 characters

blog,textl+2 byte small blob and text string 2^16-1 byte

Mediumblob,mediumtextl+3 bytes Medium blob and text string 2^24 bytes

Longblob,longtextl+4 byte large blob and text string 2^32-1 bytes

Enum (' Value ', ' value ') 1 or 2 byte enumeration: Can give an enumeration member 65,535 members

Set (' Value ', ' value ') 1,2,3,4 or 8-byte collection: Multiple members of a collection can be assigned 64 members

4, date and time type data

Type storage space Description Maximum length

Date3 byte yyyy-mm-dd format representation 1000-01-01~9999-12-31

TIME3 byte HH:MM:SS format represents time value -838:59:59~838:59:59

DATETIME8 byte yyyy-mm-dd hh:mm:ss format

TIMESTAMP4 byte YYYYMMDDHHMMSS format indicates timestamp

YEAR1 byte yyyy format year value 1901~2155

Second, the MySQL database operation

1, Login Database

MySQL parameters

-D,--database=name Open the specified database

--delimiter=name Specify Separator

-e,--Vertical Display results vertically

-H,--host=name server name

-H,--HTML provides HTML output

-X,--XML provides XML output

-P,--password[=name] Password

-P,--port=# port number

--prompt=name Setup Prompt

-u,--user=name user name

-v,--version output version information and exit

Mysql-h Server host address-u user name-P user Password

2. Exit Login

Exit

Quit

Q

3, modify the password

4. Create selection and view database

Creating a Database

Select Database

Deleting content from a database