JDBC Drivers

<!-- Maven dependency for PostgreSQL's Type 4 driver -->
<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>42.7.3</version>
</dependency>

<!-- MySQL Connector/J -->
<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.4.0</version>
</dependency>

<!-- Microsoft SQL Server -->
<dependency>
    <groupId>com.microsoft.sqlserver</groupId>
    <artifactId>mssql-jdbc</artifactId>
    <version>12.6.2.jre11</version>
</dependency>

// Gradle equivalent for PostgreSQL:
// implementation 'org.postgresql:postgresql:42.7.3'

// ── Legacy explicit registration (JDBC 3 and earlier, pre-Java 6) ──────────
// Required before drivers supported the Service Provider Interface:
try {
    Class.forName("com.mysql.jdbc.Driver");  // triggers static init -> registerDriver()
} catch (ClassNotFoundException e) {
    throw new RuntimeException("MySQL driver not found on classpath", e);
}
Connection conn = DriverManager.getConnection(
        "jdbc:mysql://localhost:3306/storedb", "app_user", "secret");

// ── Modern automatic registration via SPI (JDBC 4.0+, Java 6+) ─────────────
// No Class.forName() call needed at all — just having the driver JAR on the
// classpath is enough, because the JAR contains:
//   META-INF/services/java.sql.Driver
// whose contents are simply the driver's fully-qualified class name, e.g.:
//   org.postgresql.Driver
// DriverManager scans every JAR's META-INF/services/java.sql.Driver file at
// class-load time and registers each listed driver automatically.
Connection conn2 = DriverManager.getConnection(
        "jdbc:postgresql://localhost:5432/storedb", "app_user", "secret");
// Works immediately, with zero explicit registration code.

// You can inspect what's currently registered at runtime:
import java.util.Enumeration;
import java.sql.Driver;
import java.sql.DriverManager;

Enumeration<Driver> drivers = DriverManager.getDrivers();
while (drivers.hasMoreElements()) {
    System.out.println(drivers.nextElement().getClass().getName());
}

// ── General JDBC URL shape ──────────────────────────────────────────────
// jdbc:<subprotocol>:<driver-specific subname>

// PostgreSQL — host/port/database, query-string style properties
String pg = "jdbc:postgresql://localhost:5432/storedb?sslmode=require&connectTimeout=10";

// MySQL — similar shape, its own property names
String mysql = "jdbc:mysql://localhost:3306/storedb?useSSL=true&serverTimezone=UTC";

// Oracle thin driver — historically colon-separated host:port:SID
String oracleSid = "jdbc:oracle:thin:@localhost:1521:ORCL";
// or, for service names rather than SIDs:
String oracleService = "jdbc:oracle:thin:@//localhost:1521/ORCLPDB1";

// SQL Server — semicolon-separated key=value pairs after the host:port
String mssql = "jdbc:sqlserver://localhost:1433;databaseName=storedb;encrypt=true";

// H2 — embedded/in-memory mode, no network host at all
String h2InMemory = "jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1";

// ── Passing properties via a Properties object instead of the URL ──────────
import java.util.Properties;
import java.sql.Connection;
import java.sql.DriverManager;

Properties props = new Properties();
props.setProperty("user", "app_user");
props.setProperty("password", "secret");
props.setProperty("sslmode", "require");

Connection conn = DriverManager.getConnection(
        "jdbc:postgresql://localhost:5432/storedb", props);
// Each property's name and meaning is defined by that specific driver,
// not by the JDBC specification itself — always check the driver's docs.