Pha12thom / alx-backend-storage

alx-backend-storage

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MySQL Cheatsheet

This cheatsheet provides a quick reference for various MySQL commands and syntax for performing database operations.

Table of Contents

1. Browsing
2. Select
3. Select - Join
4. Conditions
5. Create / Open / Delete Database
6. Backup Database to SQL File
7. Restore from Backup SQL File
8. Repair Tables After Unclean Shutdown
9. Insert
10. Delete
11. Update
12. Create / Delete / Modify Table
13. Keys
14. Users and Privileges
15. Main Data Types
16. Reset Root Password

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Browsing

• SHOW DATABASES;
• SHOW TABLES;
• SHOW FIELDS FROM table / DESCRIBE table;
• SHOW CREATE TABLE table;
• SHOW PROCESSLIST;
• KILL process_number;

Select

• SELECT * FROM table;
• SELECT * FROM table1, table2;
• SELECT field1, field2 FROM table1, table2;
• SELECT ... FROM ... WHERE condition;
• SELECT ... FROM ... WHERE condition GROUP BY field;
• SELECT ... FROM ... WHERE condition GROUP BY field HAVING condition2;
• SELECT ... FROM ... WHERE condition ORDER BY field1, field2;
• SELECT ... FROM ... WHERE condition ORDER BY field1, field2 DESC;
• SELECT ... FROM ... WHERE condition LIMIT 10;
• SELECT DISTINCT field1 FROM ...
• SELECT DISTINCT field1, field2 FROM ...

Select - Join

• SELECT ... FROM t1 JOIN t2 ON t1.id1 = t2.id2 WHERE condition;
• SELECT ... FROM t1 LEFT JOIN t2 ON t1.id1 = t2.id2 WHERE condition;
• SELECT ... FROM t1 JOIN (t2 JOIN t3 ON ...) ON ...

Conditions

• field1 = value1
• field1 <> value1
• field1 LIKE 'value _ %'
• field1 IS NULL
• field1 IS NOT NULL
• field1 IS IN (value1, value2)
• field1 IS NOT IN (value1, value2)
• condition1 AND condition2
• condition1 OR condition2

Create / Open / Delete Database

• CREATE DATABASE DatabaseName;
• CREATE DATABASE DatabaseName CHARACTER SET utf8;
• USE DatabaseName;
• DROP DATABASE DatabaseName;
• ALTER DATABASE DatabaseName CHARACTER SET utf8;

Backup Database to SQL File

• mysqldump -u Username -p dbNameYouWant > databasename_backup.sql

Restore from Backup SQL File

• mysql -u Username -p dbNameYouWant < databasename_backup.sql;

Repair Tables After Unclean Shutdown

• mysqlcheck --all-databases;
• mysqlcheck --all-databases --fast;

Insert

• INSERT INTO table1 (field1, field2) VALUES (value1, value2);

Delete

• DELETE FROM table1 / TRUNCATE table1
• DELETE FROM table1 WHERE condition
• DELETE FROM table1, table2 WHERE table1.id1 = table2.id2 AND condition

Update

• UPDATE table1 SET field1=new_value1 WHERE condition;
• UPDATE table1, table2 SET field1=new_value1, field2=new_value2, ... WHERE table1.id1 = table2.id2 AND condition;

Create / Delete / Modify Table

Create

• CREATE TABLE table (field1 type1, field2 type2);
• CREATE TABLE table (field1 type1, field2 type2, INDEX (field));
• CREATE TABLE table (field1 type1, field2 type2, PRIMARY KEY (field1));
• CREATE TABLE table (field1 type1, field2 type2, PRIMARY KEY (field1,field2));
• CREATE TABLE table1 (fk_field1 type1, field2 type2, ..., FOREIGN KEY (fk_field1) REFERENCES table2 (t2_fieldA)) [ON UPDATE|ON DELETE] [CASCADE|SET NULL]
• CREATE TABLE table1 (fk_field1 type1, fk_field2 type2, ..., FOREIGN KEY (fk_field1, fk_field2) REFERENCES table2 (t2_fieldA, t2_fieldB))
• CREATE TABLE table IF NOT EXISTS;
• CREATE TEMPORARY TABLE table;

Drop

• DROP TABLE table;
• DROP TABLE IF EXISTS table;
• DROP TABLE table1, table2, ...

Alter

• ALTER TABLE table MODIFY field1 type1
• ALTER TABLE table MODIFY field1 type1 NOT NULL ...
• ALTER TABLE table CHANGE old_name_field1 new_name_field1 type1
• ALTER TABLE table CHANGE old_name_field1 new_name_field1 type1 NOT NULL ...
• ALTER TABLE table ALTER field1 SET DEFAULT ...
• ALTER TABLE table ALTER field1 DROP DEFAULT
• ALTER TABLE table ADD new_name_field1 type1
• ALTER TABLE table ADD new_name_field1 type1 FIRST
• ALTER TABLE table ADD new_name_field1 type1 AFTER another_field
• ALTER TABLE table DROP field1
• ALTER TABLE table ADD INDEX (field);

Change field order

• ALTER TABLE table MODIFY field1 type1 FIRST
• ALTER TABLE table MODIFY field1 type1 AFTER another_field
• ALTER TABLE table CHANGE old_name_field1 new_name_field1 type1 FIRST
• ALTER TABLE table CHANGE old_name_field1 new_name_field1 type1 AFTER another_field

Keys

• CREATE TABLE table (..., PRIMARY KEY (field1, field2))
• CREATE TABLE table (..., FOREIGN KEY (field1, field2) REFERENCES table2 (t2_field1, t2_field2))

Users and Privileges

• CREATE USER 'user'@'localhost';
• GRANT ALL PRIVILEGES ON base.* TO 'user'@'localhost' IDENTIFIED BY 'password';
• GRANT SELECT, INSERT, DELETE ON base.* TO 'user'@'localhost' IDENTIFIED BY 'password';
• REVOKE ALL PRIVILEGES ON base.* FROM 'user'@'host'; -- one permission only
• REVOKE ALL PRIVILEGES, GRANT OPTION FROM 'user'@'host'; -- all permissions
• FLUSH PRIVILEGES;
• `SET PASSWORD = PASSWORD('new_pass