Main way to write and always use a persistence.xml file and connecting to a database

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1"
	xmlns="http://xmlns.jcp.org/xml/ns/persistence"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
	<persistence-unit name="any-name-you-want-here">
		<!-- The persistence-unit name can be whatever you like -->
		<!-- This is the BRAIN of our project -->

		<!-- ADD (CLASSES) ENTITIES /OR MODELS CREATED FOR BY ME FOR MY APP -->
		<!-- here you include every class/ entity - as shown in the example below -->
		<!-- com.projectname.entities.classname above -->
		<!-- class only has to do with database, only add packages related to it -->
		<class>com.projectname.entities.classnamehere</class>

		<!-- ADD PROPERTIES BELOW -->
		<!-- database connectivity -->
		<properties>
			<property name="javax.persistence.jdbc.url"
				value="jdbc:mariadb://localhost:3306/db-name-here?useSSL=false" />
			<property name="javax.persistence.jdbc.user" value="root" />
			<property name="javax.persistence.jdbc.password" value="" />
			<property name="javax.persistence.jdbc.driver"
				value="org.mariadb.jdbc.Driver" />
			<property name="eclipselink.ddl-generation"
				value="create-tables" />
			<property name="eclipselink.target-database" value="MYSQL" />
			<property name="eclipselink.logging.level" value="FINE" />
		</properties>

	</persistence-unit>
</persistence>