Introduction to JDBC

 JDBC (Java Database Connectivity) is an API (Application Programming Interface) in Java that provides a standard way to interact with relational databases. It allows Java applications to connect to databases, execute SQL queries, and retrieve results. JDBC acts as a bridge between the Java application and the database, enabling platform-independent access to database systems.

Key Components of JDBC

1. JDBC API
   The JDBC API provides classes and interfaces for connecting to a database, sending SQL queries, and processing results. Some of the core interfaces include:

   • DriverManager: Manages database drivers and establishes connections.
   • Connection: Represents a connection to a specific database.
   • Statement: Used to execute SQL queries.
   • PreparedStatement: A subclass of Statement that is precompiled for parameterized queries.
   • ResultSet: Holds the data retrieved from a query.

2. JDBC Drivers
   JDBC drivers are implementations that communicate with the database. There are four types:

   • Type 1: JDBC-ODBC Bridge Driver (obsolete in modern Java versions)
   • Type 2: Native-API Driver (partially database-dependent)
   • Type 3: Network Protocol Driver (middleware-based)
   • Type 4: Thin Driver (pure Java driver that communicates directly with the database)

Features of JDBC

• Platform Independence: Write Java code once, and it works across different databases with appropriate drivers.
• Support for SQL Queries: JDBC allows executing DDL, DML, and DQL operations.
• Scalability: JDBC supports connection pooling for better performance.
• Transaction Management: Provides mechanisms to commit, rollback, or save database transactions.

Basic JDBC Workflow

1. Load the Driver
   Load the database-specific driver using Class.forName() (in modern Java, drivers load automatically if available in the classpath).

2. Establish a Connection
   Use the DriverManager.getConnection() method with the database URL, username, and password.

3. Create a Statement
   Create a Statement or PreparedStatement object to send SQL queries.

4. Execute Queries
   Use methods like executeQuery() for SELECT statements or executeUpdate() for INSERT, UPDATE, DELETE statements.

5. Process Results
   Use the ResultSet object to process and iterate through query results.

6. Close Resources
   Always close the ResultSet, Statement, and Connection objects to release resources.