Create mysql.md (#941)

Cheatsheet for MySQL

mysql.md

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+---
+title: MySql
+---
+ ### Create / Delete Database
+    CREATE DATABASE dbNameYouWant
+    CREATE DATABASE dbNameYouWant CHARACTER SET utf8
+    DROP DATABASE dbNameYouWant
+    ALTER DATABASE dbNameYouWant 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
+### 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 GROUPBY field
+    SELECT ... FROM ... WHERE condition GROUPBY 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
+    
+### Insert    
+    INSERT INTO table1 (field1, field2, ...) VALUES (value1, value2, ...)
+    
+### Delete
+    DELETE FROM table1 / TRUNCATE table1
+    DELETE FROM table1 WHERE condition
+    DELETE FROM table1, table2 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
+    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
+      
+    SET PASSWORD = PASSWORD('new_pass')
+    SET PASSWORD FOR 'user'@'host' = PASSWORD('new_pass')
+    SET PASSWORD = OLD_PASSWORD('new_pass')
+      
+    DROP USER 'user'@'host'
+    host ‘%’ indicates any host.
+    
+    
+### Main Data Types
+     TINYINT (1o: -217+128) SMALLINT (2o: +-65 000)
+     MEDIUMINT (3o: +-16 000 000) INT (4o: +- 2 000 000 000)
+     BIGINT (8o: +-9.10^18)
+     
+     Precise interval: -(2^(8*N-1)) -> (2^8*N)-1
+     /!\ INT(2) = "2 digits displayed" -- NOT "number with 2 digits max"
+      
+     FLOAT(M,D) DOUBLE(M,D) FLOAT(D=0->53)
+     /!\ 8,3 -> 12345,678 -- NOT 12345678,123!
+      
+     TIME (HH:MM) YEAR (AAAA) DATE (AAAA-MM-JJ) DATETIME (AAAA-MM-JJ HH:MM; années 1000->9999)
+     TIMESTAMP (like DATETIME, but 1970->2038, compatible with Unix)
+     
+     VARCHAR (single-line; explicit size) TEXT (multi-lines; max size=65535) BLOB (binary; max size=65535)
+     Variants for TEXT&BLOB: TINY (max=255) MEDIUM (max=~16000) LONG (max=4Go)
+     Ex: VARCHAR(32), TINYTEXT, LONGBLOB, MEDIUMTEXT
+     
+     ENUM ('value1', 'value2', ...) -- (default NULL, or '' if NOT NULL)
+    
+### Reset Root Password
+    <code>$ /etc/init.d/mysql stop
+    $ mysqld_safe --skip-grant-tables
+    $ mysql # on another terminal
+    mysql> UPDATE mysql.user SET password=PASSWORD('new_pass') WHERE user='root';
+    ## Switch back to the mysqld_safe terminal and kill the process using Control + \
+    $ /etc/init.d/mysql start</code>