268 lines
5.8 KiB
Markdown
268 lines
5.8 KiB
Markdown
---
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title: MySQL
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updated: 2020-07-05
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category: Databases
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---
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### Browsing
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```sql
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SHOW DATABASES;
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SHOW TABLES;
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SHOW FIELDS FROM table / DESCRIBE table;
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SHOW CREATE TABLE table;
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SHOW PROCESSLIST;
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KILL process_number;
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```
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### Select
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```sql
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SELECT * FROM table;
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SELECT * FROM table1, table2;
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SELECT field1, field2 FROM table1, table2;
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SELECT ... FROM ... WHERE condition
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SELECT ... FROM ... WHERE condition GROUP BY field;
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SELECT ... FROM ... WHERE condition GROUP BY field HAVING condition2;
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SELECT ... FROM ... WHERE condition ORDER BY field1, field2;
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SELECT ... FROM ... WHERE condition ORDER BY field1, field2 DESC;
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SELECT ... FROM ... WHERE condition LIMIT 10;
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SELECT DISTINCT field1 FROM ...
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SELECT DISTINCT field1, field2 FROM ...
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```
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### Select - Join
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```sql
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SELECT ... FROM t1 JOIN t2 ON t1.id1 = t2.id2 WHERE condition;
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SELECT ... FROM t1 LEFT JOIN t2 ON t1.id1 = t2.id2 WHERE condition;
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SELECT ... FROM t1 JOIN (t2 JOIN t3 ON ...) ON ...
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```
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### Conditions
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```sql
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field1 = value1
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field1 <> value1
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field1 LIKE 'value _ %'
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field1 IS NULL
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field1 IS NOT NULL
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field1 IS IN (value1, value2)
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field1 IS NOT IN (value1, value2)
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condition1 AND condition2
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condition1 OR condition2
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```
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### Create / Open / Delete Database
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```sql
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CREATE DATABASE DatabaseName;
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CREATE DATABASE DatabaseName CHARACTER SET utf8;
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USE DatabaseName;
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DROP DATABASE DatabaseName;
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ALTER DATABASE DatabaseName CHARACTER SET utf8;
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```
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### Backup Database to SQL File
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```bash
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mysqldump -u Username -p dbNameYouWant > databasename_backup.sql
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```
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### Restore from backup SQL File
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```bash
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mysql -u Username -p dbNameYouWant < databasename_backup.sql;
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```
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### Repair Tables After Unclean Shutdown
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```bash
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mysqlcheck --all-databases;
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mysqlcheck --all-databases --fast;
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```
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### Insert
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```sql
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INSERT INTO table1 (field1, field2) VALUES (value1, value2);
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```
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### Delete
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```sql
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DELETE FROM table1 / TRUNCATE table1
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DELETE FROM table1 WHERE condition
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DELETE FROM table1, table2 WHERE table1.id1 =
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table2.id2 AND condition
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```
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### Update
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```sql
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UPDATE table1 SET field1=new_value1 WHERE condition;
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UPDATE table1, table2 SET field1=new_value1, field2=new_value2, ... WHERE
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table1.id1 = table2.id2 AND condition;
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```
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### Create / Delete / Modify Table
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#### Create
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```sql
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CREATE TABLE table (field1 type1, field2 type2);
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CREATE TABLE table (field1 type1, field2 type2, INDEX (field));
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CREATE TABLE table (field1 type1, field2 type2, PRIMARY KEY (field1));
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CREATE TABLE table (field1 type1, field2 type2, PRIMARY KEY (field1,field2));
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```
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```sql
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CREATE TABLE table1 (fk_field1 type1, field2 type2, ...,
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FOREIGN KEY (fk_field1) REFERENCES table2 (t2_fieldA))
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[ON UPDATE|ON DELETE] [CASCADE|SET NULL]
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```
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```sql
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CREATE TABLE table1 (fk_field1 type1, fk_field2 type2, ...,
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FOREIGN KEY (fk_field1, fk_field2) REFERENCES table2 (t2_fieldA, t2_fieldB))
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```
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```sql
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CREATE TABLE table IF NOT EXISTS;
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```
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```sql
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CREATE TEMPORARY TABLE table;
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```
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#### Drop
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```sql
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DROP TABLE table;
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DROP TABLE IF EXISTS table;
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DROP TABLE table1, table2, ...
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```
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#### Alter
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```sql
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ALTER TABLE table MODIFY field1 type1
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ALTER TABLE table MODIFY field1 type1 NOT NULL ...
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ALTER TABLE table CHANGE old_name_field1 new_name_field1 type1
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ALTER TABLE table CHANGE old_name_field1 new_name_field1 type1 NOT NULL ...
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ALTER TABLE table ALTER field1 SET DEFAULT ...
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ALTER TABLE table ALTER field1 DROP DEFAULT
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ALTER TABLE table ADD new_name_field1 type1
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ALTER TABLE table ADD new_name_field1 type1 FIRST
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ALTER TABLE table ADD new_name_field1 type1 AFTER another_field
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ALTER TABLE table DROP field1
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ALTER TABLE table ADD INDEX (field);
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```
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#### Change field order
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```sql
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ALTER TABLE table MODIFY field1 type1 FIRST
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ALTER TABLE table MODIFY field1 type1 AFTER another_field
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ALTER TABLE table CHANGE old_name_field1 new_name_field1 type1 FIRST
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ALTER TABLE table CHANGE old_name_field1 new_name_field1 type1 AFTER
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another_field
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```
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### Keys
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```sql
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CREATE TABLE table (..., PRIMARY KEY (field1, field2))
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CREATE TABLE table (..., FOREIGN KEY (field1, field2) REFERENCES table2
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(t2_field1, t2_field2))
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```
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### Users and Privileges
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```sql
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CREATE USER 'user'@'localhost';
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GRANT ALL PRIVILEGES ON base.* TO 'user'@'localhost' IDENTIFIED BY 'password';
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GRANT SELECT, INSERT, DELETE ON base.* TO 'user'@'localhost' IDENTIFIED BY 'password';
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REVOKE ALL PRIVILEGES ON base.* FROM 'user'@'host'; -- one permission only
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REVOKE ALL PRIVILEGES, GRANT OPTION FROM 'user'@'host'; -- all permissions
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FLUSH PRIVILEGES;
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```
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```sql
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SET PASSWORD = PASSWORD('new_pass');
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SET PASSWORD FOR 'user'@'host' = PASSWORD('new_pass');
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SET PASSWORD = OLD_PASSWORD('new_pass');
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```
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```sql
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DROP USER 'user'@'host';
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```
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Host ‘%’ indicates any host.
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### Main Data Types
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```sql
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TINYINT (1o: -128 to +127)
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SMALLINT (2o: +-65 000)
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MEDIUMINT (3o: +-16 000 000)
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INT (4o: +- 2 000 000 000)
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BIGINT (8o: +-9.10^18)
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```
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```sql
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Precise interval: -(2^(8*N-1)) -> (2^8*N)-1
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```
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⚠ INT(2) = "2 digits displayed" -- NOT "number with 2 digits max"
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```sql
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FLOAT(M,D)
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DOUBLE(M,D)
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FLOAT(D=0->53)
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```
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⚠ 8,3 -> 12345,678 -- NOT 12345678,123!
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```sql
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TIME (HH:MM)
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YEAR (AAAA)
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DATE (AAAA-MM-JJ)
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DATETIME (AAAA-MM-JJ HH:MM; années 1000->9999)
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TIMESTAMP (like DATETIME, but 1970->2038, compatible with Unix)
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```
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```sql
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VARCHAR (single-line; explicit size)
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TEXT (multi-lines; max size=65535)
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BLOB (binary; max size=65535)
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```
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Variants for TEXT&BLOB: `TINY` (max=255), `MEDIUM` (max=~16000), and `LONG` (max=4Go). Ex: `VARCHAR(32)`, `TINYTEXT`, `LONGBLOB`, `MEDIUMTEXT`
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```sql
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ENUM ('value1', 'value2', ...) -- (default NULL, or '' if NOT NULL)
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```
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### Reset Root Password
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```bash
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$ /etc/init.d/mysql stop
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```
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```bash
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$ mysqld_safe --skip-grant-tables
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```
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```bash
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$ mysql # on another terminal
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mysql> UPDATE mysql.user SET password=PASSWORD('new_pass') WHERE user='root';
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```
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```bash
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## Switch back to the mysqld_safe terminal and kill the process using Control + \
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$ /etc/init.d/mysql start
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```
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Your commands may vary depending on your OS.
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