Install MariaDB on Debian 12

Step 1 – Install and secure

apt update && apt upgrade -y
apt install -y mariadb-server
systemctl enable --now mariadb
mysql_secure_installation

Step 2 – Create database and user

CREATE DATABASE appdb CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
CREATE USER 'appuser'@'localhost' IDENTIFIED BY 'StrongPass!';
GRANT ALL PRIVILEGES ON appdb.* TO 'appuser'@'localhost';
FLUSH PRIVILEGES;

Key /etc/mysql/mariadb.conf.d/50-server.cnf settings

[mysqld]
innodb_buffer_pool_size = 1G
character-set-server    = utf8mb4
collation-server        = utf8mb4_unicode_ci