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I. Mysql Basic Operation Command:

(1) View database list information:

show databases;

(2) Check the data table information in the database:

use database name; //view database show tables; //View Data Sheet

(3) Display the structure of the data table (fields):

describe database name;

II. SQL statement overview:

(a) SQL language:

Structured Query Language; a standard language for relational databases; used to maintain and manage databases, such as data queries, data updates, access control, object management, etc.

(b) SQL classification:

DDL: Data Definition Language;DML: Data Manipulation Language;DQL: Data Query Language;DCL: Data Control Language;

(1) DDL operation command:

DDL statements are used to create database objects, such as libraries, tables, indexes, etc.

1. Creation:

create database name; //create database create table table name (field definition...) //Create a data table

For example, the following creates an info table containing ID number, grade, name and address:

Primary key: identifies the unique entity object in the table. It is unique and non-empty (both must be satisfied).

mysql> use team; //Enter Database changed mysql> create table info( //create a table named info -> id int(4) not null, -> name char(10) not null, -> address varchar(50) default 'Beijing', //default is default -> score decimal, -> primary key (id)); //ID as primary key

Remarks:

General use char type storage fixed data such as ID number (18) telephone number gender…

Varchar for variable data

float: floating point type, containing 4 bytes, 32 bits, the value range is-3.4E38~3.4E38 (7 significant bits)

double: double precision real type, including 8 bytes, 64bit value range-1.7E308~1.7E308 (15 significant bits)

decimal: numeric, 128bit, no loss of precision, often used in bank account calculations. (28 significant bits)

2. Delete:

drop table [database name.] table name //delete the specified database drop database name //Delete the specified database

(2) DML operation command:

DML statements are used to manage data in tables, including the following operations:

insert: insert new data;update: update existing data;delete: delete unwanted data;

1. Insert

insert into table name (field 1, field 2...) values (value of field 1, value of field 2...)

For example, based on the previous table, let's do the following insertion:

mysql> insert into info (id,name,address,score) values (001,'zhangsan','Shanghai', 99);//insert a message named zhangsan, id 1, Shanghai, score 99 mysql> insert into info (id,name,address,score) values (002,'lisi',' Hangzhou', 88);//insert a message named lisi, id 2, Hangzhou, score 88 mysql> insert into info (id,name,address,score) values (003,'wangwu', default,77);//Insert a message named zhaowu, id number 3, Nanjing, score 77

2, modify, update (update)

update table name set field name 1= value 1 where conditional expression

For example, the following table adds an address to jack:

Enter the following command:

update info set address='Wuhan' where name='jack';

3, delete (delete)

delete from table name where conditional expression detele from table name //Delete the entire table

(3) DQL operation command:

Used to find qualified data records from the data table. No condition can be specified when querying.

Command: Select

1. No conditions specified:

select field 1 from table name

2. Specify condition query:

select field 1 from table name where conditional expression

(4) DCL operation command:

1. Set user permissions (if the user does not exist, create a new user):

GRANT Permission List ON Database Name. Table Name TO User Name @ Source Address [ IDENTIFIED BY 'Password']

2. View user permissions:

SHOW GRANTS FOR Username @ Source Address

3. Revoke the user's rights:

REVOKE Permission List ON Database Name. Table Name FROM User Name @ Source Address

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