MySQL First Knowledge 01

Recently began to learn MySQL so the two days to learn a brief summary of the knowledge

1.status displaying database information

2. Data type:

A. String:

CHAR (m): fixed-length character with a maximum of 255 characters;

varchar (m): variable-length string, up to 255 characters

B. Integral type: int

C. Floating point: float[(m,d)] m, Width indicator, representing the sum of data lengths around the decimal point; D, precision indicator, indicating the number of digits to the right of the decimal point

D.set: Represents a combination of multiple values

E.enum: Similar to set, representing multiple values, but only one can be selected

F.text/blob: Used to save 255 to 65,535 characters, text is case-insensitive, blobs are case-sensitive

3. Common permissions:

Global Administrative permissions:

File: Read and write files on the MySQL server;

Process: Displays or kills other users ' service processes

RELOAD: Overload access Control table, refresh log, etc.

SHUTDOWN: Turn off MySQL service

Database/database table/Data column permissions:

Alter: Modify an existing data table (Add/Delete column) and index

Create: Create a new database or data table

Delete: Deleting records from a table

Drop: Delete a data table or database

Index: Create or delete indexes

INSERT: Add a table record

Selete: Display/Search Table records

UPDATE: Modify a record that already exists in the table

(Permissions this paragraph from a blog, the specific is not clear, then feel very helpful to understand, so recorded)

4.mysql Common Operations (commands):

A. Login:

Mysql-uroot-p (when password is available)

Mysql-u root (login without password)

B. Operation:

MySQL >create database; (creating databases)

> show databases; (View all current databases)

> Use Dataname; (acting on a specific database)

> Show tables; (View the tables in the database)

> CREATE table User (name char (m), passwd char (m));(Creating tables user, and two of these fields name,passwd)

> describe user; (view field of table user)

> INSERT into user values ();(inserts several records into the table)

> select * from User; (View all data in table user)

> Delete from user where name = "";(remove data from table)

> Update user set name = "WHERE name =" ";(modify data in the table)

>exit (Exit Database)

Note: ";" as Oh command Terminator, essential

These are some of today's summary, follow-up will continue to update

　　　

MySQL First Knowledge 01