MySQL common DDL, DML, DCL language finishing

DDL

---- Data Definition Language database definition language such as create procedure

Create a database

CREATE DATABASE [IF NOT EXISTS] DBNAME [CHARACTER SET 'CHAR_NAME'] [COLLATE 'COLL_NAME']

Modify: ALTER deleted: DROP

 

DML

---- Data Manipulation Language Data Manipulation Language

Such as insert, delete, update, select (insert, delete, modify, retrieve) into modified data

 

mysql>INSERT INTO students (Name,Gender,teacher) VALUE ('lujunyi','M','mage'),('wusong','M','zhuima');

mysql>INSERT INTO students SET Name='lujunyi',Gender='M',tearcher='zhuima';

 

update data

mysql>UPDATE tb_name SET column=value WHERE column=value;

mysql>UPDATE students SET Course='mysql' WHERE Name='lujunyi';

 

Replace data:

 UPDATE and use, as long as you can REPLACE will replace UPDATE

 

delete data:

mysql>DELETE FROM tb_name WHERE conditions;

mysql>DELETE FROM students WHERE Course='mysql';

Empty Table:

mysql>TRUNCATE tb_name

 

Query data

Single-table query:

mysql>SELECT [DISTINCT] column FROM tb_name WHERE CONDITION;

 

EXAMPLE:

# Basic projection inquiry

mysql>SELECT Name,teacher FROM students WHERE Name='wusong';

 

# Repeatable results show only once

mysql>SELECT DISTINCT Gender FROM students;

 

# Combination of conditions, use AND, OR, NOT, XOR combination of the plurality of conditions

mysql>SELECT * FROM students WHERE Age>20 AND Gender='M';

 

# Using BETWEEN ... AND ... filter out data between the ages of 20-25

mysql>SELECT * FROM students WHERE Age BETWEEN 20 AND 25;

 

# Name starts with a query of data Y,% represents any character of any length, represents any single character _

mysql>SELECT * FROM student WHERE Name LIKE 'Y%';

 

# Use regular expressions to match the query, or keywords for the RLINK REGEXP

mysql> SELECT * FROM students WHERE Name RLINK '^[MNY].*$';

 

# Using IN keyword, the condition is defined in a list. IS with keywords, indicating whether the condition is zero (IS NULL or IS NOT NULL)

mysql>SELECT * FROM students WHERE Age IN (20,22,24);

 

# The results of the query to sort

mysql>SELECT * FROM students ORDER BY Name {ASC|DESC};

 

# Alias ​​display query results

mysql>SELECT Name AS Stu_Name FROM students;

 

After several #LIMIT defined query results, LIMIT 2,3 represents the offset data 2, data 3 taken

mysql>SELECT * FROM students LIMIT 2;

 

Averaging #: AVG (), maximum: MAX () minimum value MIN () Number: COUNT () sum: SUM ()

mysql>SELECT AVG(age) FROM students;

 

# GROUP BY grouping

mysql>SELECT Age, Gender FROM students GROUP BY Gender;

 

# Alias: AS

mysql>SELECT COUNT(Age) AS Num,Age FROM students GROUP BY Age;

 

# Filter: HAVING

mysql>SELECT COUNT(Age) AS Num,Age FROM students GROUP BY Age HAVING Num>2;

 

Multi-table query:

# Specify which fields have been connected to two tables

mysql>SELECT students.Name,courses.Cname FROM students,courses WHERE students.CID1 = courses.CID;

 

# Alias ​​connection

mysql>SELECT students.Name,courses.Cname FROM students,courses WHERE students.CID1 = courses.CID;

 

# Left outer join ... LEFT JOIN ... ON ...

mysql>SELECT s.Name,c.Cname FROM students AS s LEFT JOIN courses AS c ON s.CID1=c.CID;

 

# Right outer join ... RIGHT JOIN ... ON ...

mysql>SELECT s.Name,c.Cname FROM students AS s RIGHT JOIN courses AS c ON s.CID1=c.CID;

 

Subqueries

# Query data older than the average age of

mysql>SELECT * FROM students WHERE Age > (SELECT AVG(Age) FROM students);

 

# Using subqueries in the FROM

mysql>SELECT Name,Age FROM (SELECT * FROM students WHERE CID IN (2,3)) AS t WHERE Age>20;

 

# Joint inquiry

mysql>(SELECT Name,Age FROM students) UNION (SELECT Tname,Age FROM tutors);

 

Create a view

CREATE VIEW VIEW_NAME AS SELECT....

 

DCL

---- Data Control Language database control language such as grant, deny, revoke, etc. Only administrators have permission to do so.

Create a user

mysql>CREATE USER 'USERNAME'@'HOST' IDENTIFIED BY 'PASSWORD'

 

delete users

MySQL > DROP  the USER  ' USERNAME ' @ ' HOSHOST support wildcards

 

_: Any single character

%: Any number of characters

Authorize

mysql>GRANT pri1,pri2...ON DB_NAME.TB_NAME TO 'USERNAME'@'HOST' [IDENTIFIED BY 'PASSWORD']

 

Deauthorize

mysql>REVOKE pri1,pri2...ON DB_NAME.TB_NAME FROM 'USERNAME'@'HOST';

 

Check Authorization

mysql>SHOW GRANTS FOR 'USERNAME'@'HOST';

 

EXAMPLE:

mysql>CREATE USER 'lujunyi'@'%' IDENTIFIED BY '123456';

mysql>SHOW GRANTS FOR 'lujunyi'@'%';

mysql>GRANT ALL PRIVILEGES ON testdb.* TO 'lujunyi'@'%';