PHP mobile Internet Development notes (6)-MySQL database basic review

Source: Internet
Author: User

I recently read some architectural materials, but found that the basic knowledge is not very strong. In the next period, I will summarize the basic knowledge on a regular basis.

I. Data Types

1. Integer

Data Type Storage space Description Value Range
TINYINT 1 byte Very small integer Signed value:-128 ~ 127
Unsigned value: 0 ~ 255
SMALLINT 2 bytes Small integer Signed value:-32768 ~ 32767
Unsigned value: 0 ~ 65535
MEDIUMNT 3 bytes An integer of medium size Signed value:-8388608 ~ 8388607
Unsigned value: 0 ~ 16777215
INT 4 bytes Standard integer Signed value:-2147483648 ~ 2147483647
Unsigned value: 0 ~ 4294967295
BIGINT 8 bytes Big integer  

2. Floating Point

Data Type Storage space Description Value Range
FLOAT 4 bytes But the precision Floating Point Number  
DOUBLE 8 bytes Double-precision floating point number  
DECIMAL (M, D) Custom In string format  

3. string type

Type Storage space Description Maximum length
Char [(M)] MB bytes Fixed Length string MB bytes
Varchar [(M)] L + 1 byte Variable Length string MB bytes
Tinyblog, tingtext L + 1 byte Very small blob and text string 2 ^ 8 characters
Blog, text L + 2 bytes Small BLOB and text string 2 ^ 16-1 bytes
Mediumblob, mediumtext L + 3 bytes Moderate BLOB and text string 2 ^ 24 bytes
Longblob, longtext L + 4 bytes Large BLOB and text string 2 ^ 32-1 bytes
Enum ('value', 'value ') 1 or 2 bytes Enumeration: You can assign an enumeration member. 65535 members
Set ('value', 'value ') 1, 2, 3, 4, or 8 bytes Set: You can assign multiple set members. 64 members

4. Date and Time Data
Type Storage space Description Maximum length
Date 3 bytes YYYY-MM-DD format Representation 1000-01-01 ~ 9999-12-31
TIME 3 bytes Hh: mm: ss format indicates the time value -838: 59: 59 ~ 838: 59: 59
DATETIME 8 bytes YYYY-MM-DD hh: mm: ss format  
TIMESTAMP 4 bytes The format of YYYYMMDDhhmmss indicates the timestamp.  
YEAR 1 byte Year Value in YYYY format 1901 ~ 2155
Ii. MySQL database operations

1. log on to the database

Mysql Parameters

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

-- Delimiter = name specifies the delimiter

-E, -- vertical display result

-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: Set the prompt

-U, -- user = name Username

-V, -- version: Output version information and exit

Mysql-h server host address-u user name-p User Password

2. log out

Exit

Quit

\ Q

3. Change the password

4. Create, select, and view Databases

Create a database

Select Database

Delete database content

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