Mysql

Install

Info

Installation flow needs an active VPN

sudo apt update
sudo apt install gnupg
cd /tmp
wget https://dev.mysql.com/get/mysql-apt-config_0.8.22-1_all.deb
sudo dpkg -i mysql-apt-config*
sudo apt update
sudo apt install mysql-server
sudo mysql_secure_installation

Data Types

String:

Data Type	Range	Storage size
CHAR(size)	Fixed length, 0 to 255 chars	1 to 255 bytes
VARCHAR(size)	Variable length, 0 to 65,535 chars	1 to 65,535 bytes
TEXT	Up to 65,535 chars	Up to 65,535 bytes
MEDIUMTEXT	Up to 16,777,215 chars	Up to 16,777,215 bytes
LONGTEXT	Up to 4,294,967,295 chars	Up to 4,294,967,295 bytes
TINYBLOB	Up to 255 bytes	Up to 255 bytes
BLOB	Up to 65,535 bytes	Up to 65,535 bytes
MEDIUMBLOB	Up to 16,777,215 bytes	Up to 16,777,215 bytes
LONGBLOB	Up to 4,294,967,295 bytes	Up to 4,294,967,295 bytes
ENUM	Enumerated list of values	Depends on values
SET	Set of values	Depends on values

Numeric:

Data Type	Range (signed) (Default)	Range (unsigned)	Storage size
TINYINT(size)	-128 to 127	0 to 255	1 byte
SMALLINT(size)	-32,768 to 32,767	0 to 65,535	2 bytes
MEDIUMINT(size)	-8,388,608 to 8,388,607	0 to 16,777,215	3 bytes
INT(size), INTEGER(size)	-2,147,483,648 to 2,147,483,647	0 to 4,294,967,295	4 bytes
BIGINT(size)	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807	0 to 18,446,744,073,709,551,615	8 bytes
FLOAT(size, d)	-3.402823466E+38 to 3.402823466E+38	Not applicable	4 bytes
DOUBLE(size, d)	-1.7976931348623157E+308 to 1.7976931348623157E+308	Not applicable	8 bytes
DECIMAL(size, d), DEC(size, d)	Depends on the precision and scale	Depends on the precision and scale	Varies
BIT(size)	Not applicable	1 to 64	Varies

Date and time:

Data Type	Range	Storage size
DATE	1000-01-01 to 9999-12-31	3 bytes
DATETIME(fsp)	1000-01-01 00:00:00 to 9999-12-31 23:59:59	8 bytes
TIMESTAMP(fsp)	1970-01-01 00:00:01 UTC to 2038-01-19 03:14:07 UTC	4 bytes
TIME(fsp)	-838:59:59 to 838:59:59	3 bytes
YEAR	1901 to 2155	1 byte

Boolean:

Data Type Range Storage size

BOOL, BOOLEAN 0 or 1 1 byte
Full Data Types

Export/Import

Import data to database:

mysql [-h <host>] -u <username: root> -p <db_name> < <file_path/file_name.sql>

Export data from database:
```
mysqldump [-h <host>] -u <username: root> -p <db_name> > <file_path/file_name.sql>
```
More options:
- --no-data: Dump only the table structure (schema); no row data is exported.
- --single-transaction: Makes a snapshot without locking tables (InnoDB only).
- --quick: Streams rows to the output file instead of buffering (good for large DBs).
- --routines: Exports stored procedures and functions
- --triggers: Exports triggers (included by default, but good to be explicit).
- --events: Exports scheduled events.
- --add-drop-table: Add DROP TABLE IF EXISTS before CREATE.
- --compress: Use compression for client/server communication (saves bandwidth).
- --result-file=path: Write directly to file (avoids shell redirection).
- --databases db1 db2: Dump listed databases.
- --all-databases: Dump all databases.
- --set-gtid-purged=OFF|ON|AUTO: Include or omit GTID info.

Shell

Connect:
```
mysql -u root -p
```
Run command without connection:
```
mysql -u root -p <<< 'SHOW DATABASES;'
```
Vertical show fields:
```
SELECT * FROM <table_name>\G
```

User

Show all users:
```
SELECT user, host FROM mysql.user
```

Accepting all IPs:

UPDATE mysql.user SET host='<host: %>' WHERE user='<user: root>'

Create user:

CREATE USER '<username>'@'localhost' IDENTIFIED BY '<password>'

Drop user:
Change pass for any user:

Change pass of root user:

ALTER USER 'root'@'%' IDENTIFIED BY '<new_password>'

Add all privileges to user for one database:

GRANT ALL PRIVILEGES ON <db_name>.* TO '<user>'@'localhost'

Database

Show all database:
```
SHOW DATABASES
```
Create db:
```
CREATE DATABASE <db_name>
```
Drop database:
```
DROP DATABASE <db_name>
```
Show database owner:
```
SHOW processlist
```
Change db owner:
Connect to database:
```
USE <db_name>
```
Get size of databases:

sql SELECT table_schema "<db_name>", ROUND(SUM(data_length + index_length) / 1024 / 1024, 1) "DB Size in MB" FROM information_schema.tables GROUP BY table_schema

Tables

Show all of db tables:
```
SHOW TABLES
```
Show table schema:
```
DESCRIBE <table_name>
```
Show table full schema:
```
SHOW FULL COLUMNS FROM <table_name>
```

Create table simple:

CREATE TABLE <table_name> (id INT NOT NULL AUTO_INCREMENT, <column2> <datatype>, PRIMARY KEY(id))

Create table complex:

CREATE TABLE <table_name> (
    id BINARY(16) PRIMARY KEY,  # UUID
    created DATETIME(6) NOT NULL,
    <column3> INT NOT NULL DEFAULT 0,
    <column4> BINARY(16) UNIQUE NOT NULL,  # FK (1:1)

    INDEX (<column3>),  # custom index
    FOREIGN KEY (<column4>) REFERENCES <other_table>(id)  # automatically will create an index
);

Create table based on other table:
Delete table:
```
DROP TABLE <table_name>
```
Show indexes:
```
SHOW INDEXES IN <table_name>
```

Row

Updating row:

UPDATE <table_name> SET <column1>=<value>

Create row in table:

INSERT INTO <table_name> (column1, column2) VALUES (value1, value2)

Create row in table base on other table rows:

Delete row in table:

DELETE FROM <table_name> WHERE <column1>=<value>

Index

Partial index:

CREATE [UNIQUE] INDEX <index_name> ON <table> (<column1, column2>) WHERE <conditions>

Other

Version:
```
SHOW VARIABLES LIKE "%version%";
```