JDBC stands for Java Database Connectivity. It is an API that enables Java programs to execute SQL statements, retrieve results, and interact with relational databases.

Key Features:
• Platform-independent database access
• Supports standard SQL queries
• Allows CRUD operations (Create, Read, Update, Delete)
• Part of the Java Standard Edition (SE)

JDBC architecture consists of two main layers:
1. JDBC API – Provides application-level interface for Java programs to interact with databases.
2. JDBC Driver – A set of classes that implements the JDBC interfaces for a specific database.

Types of JDBC Drivers:
Driver Type Description Example
Type 1 JDBC-ODBC Bridge driver Obsolete
Type 2 Native-API driver Oracle OCI
Type 3 Network Protocol driver Middleware-based
Type 4 Thin driver (pure Java) MySQL JDBC driver

Type 4 is the most widely used as it is platform-independent and efficient.

The core JDBC interfaces and classes:
Class/Interface Description
DriverManager Manages a list of database drivers
Connection Establishes a connection to the database
Statement Executes static SQL queries
PreparedStatement Executes parameterized queries
ResultSet Holds the result of a query
SQLException Handles errors

1. Load the JDBC Driver
   javaCopy codeClass.forName("com.mysql.cj.jdbc.Driver");
2. Establish the Connection
   javaCopy codeConnection con = DriverManager.getConnection(
   "jdbc:mysql://localhost:3306/testdb", "root", "password");
3. Create a Statement
   javaCopy codeStatement stmt = con.createStatement();
4. Execute the Query
   javaCopy codeResultSet rs = stmt.executeQuery("SELECT * FROM employees");
5. Process the Result
   javaCopy codewhile(rs.next()) {
   System.out.println(rs.getInt(1) + " " + rs.getString(2));
   }
6. Close the Connection
   javaCopy codecon.close();

Feature Statement PreparedStatement
SQL Injection Protection No Yes
Performance Lower (parses every time) Higher (precompiled)
Use Case Simple, static SQL Repeated, parameterized SQL
Example: Using PreparedStatement
javaCopy codePreparedStatement ps = con.prepareStatement("INSERT INTO students VALUES (?, ?)");
ps.setInt(1, 101);
ps.setString(2, "John");
ps.executeUpdate();

By default, JDBC auto-commits each SQL statement. To perform transactions:
javaCopy codecon.setAutoCommit(false);
// Execute multiple queries
con.commit(); // or con.rollback();

Execute multiple statements together to improve performance:
javaCopy codePreparedStatement ps = con.prepareStatement("INSERT INTO logs VALUES (?, ?)");
for(int i=1; i<=100; i++) {
ps.setInt(1, i);
ps.setString(2, "Log " + i);
ps.addBatch();
}
ps.executeBatch();

JDBC provides SQLException for error handling.
javaCopy codetry {
// JDBC code
} catch (SQLException e) {
System.out.println("Error: " + e.getMessage());
}
You can also use:
• e.getErrorCode()
• e.getSQLState()

Database JDBC URL
MySQL jdbc:mysql://localhost:3306/dbname
PostgreSQL jdbc:postgresql://localhost:5432/dbname
Oracle jdbc:oracle:thin:@localhost:1521:orcl
SQLite jdbc:sqlite:path_to_db_file

• Always close Connection, Statement, and ResultSet.
• Use try-with-resources for automatic closing.
• Prefer PreparedStatement to avoid SQL injection.
• Use connection pooling (like HikariCP) in real-world apps.
• Avoid hardcoded queries – use parameterized queries or ORM (e.g., Hibernate).