JDBC: Java Database Connectivity

• JDBC (Java Database Connectivity) facilitates Java applications interacting with databases.

JDBC Connectivity Model

• Establishes a connection between a Java application and a database.
• Uses JDBC drivers to communicate with different database systems.
• Involves loading the driver, establishing a connection, executing queries, and processing results.

Database Programming

• Involves connecting to a database using JDBC.
• Creating SQL queries to retrieve or modify data.
• Processing results obtained from the database.
• Managing database connections and resources efficiently.

Connecting to the Database

• Requires specifying the database URL, username, and password.
• Uses the DriverManager.getConnection() method to establish a connection.
• Proper error handling is crucial to manage connection failures.

Creating a SQL Query

• Involves formulating SQL statements to interact with the database.
• Can be SELECT, INSERT, UPDATE, or DELETE statements.
• Requires understanding the database schema and SQL syntax.
• Can use Statement, PreparedStatement, or CallableStatement objects.

Getting the Results

• Involves retrieving data from the database after executing a query.
• Uses ResultSet object to access the retrieved data.
• Data can be accessed using column names or indexes.
• Should handle SQLException to manage potential errors.

Updating Database Data

• Involves modifying data in the database using SQL UPDATE, INSERT, or DELETE statements.
• Requires executing these statements using Statement, PreparedStatement, or CallableStatement objects.
• Ensure proper error handling and transaction management for data integrity.

Error Checking and the SQLException Class

• SQLException is thrown when an error occurs during database access.
• Provides information about the error, such as error code and SQL state.
• Proper error handling is essential to manage database exceptions gracefully.
• Catching SQLException allows the application to handle database-related issues.

The SQLWarning Class

• SQLWarning provides information about database warnings.
• Warnings are less severe than exceptions and do not halt execution.
• Can be chained to provide multiple warnings.
• Accessed through Connection, Statement, and ResultSet objects.

The Statement Interface

• Used to execute static SQL statements.
• Created using the Connection.createStatement() method.
• Methods include executeQuery(), executeUpdate(), and close().
• Vulnerable to SQL injection attacks if not used carefully.

PreparedStatement

• Precompiled SQL statements for repeated execution.
• Prevents SQL injection attacks by parameterizing queries.
• Created using the Connection.prepareStatement() method.
• Parameters are set using setXXX() methods.

CallableStatement

• Used to execute stored procedures in the database.
• Created using the Connection.prepareCall() method.
• Parameters can be input, output, or both.
• Results are retrieved using getXXX() methods after execution.

The ResultSet Interface

• Represents the result of a database query.
• Allows navigation through the result set using methods like next() and previous().
• Provides methods to retrieve data from columns, such as getString(), getInt(), etc.
• Must be closed after use to release resources.

Updatable Result Sets

• Allows updating the database directly through the ResultSet object.
• Requires specific database and driver support.
• Methods include updateXXX(), insertRow(), updateRow(), and deleteRow().
• Changes are reflected in the database immediately.

JDBC Types

• Mapping of SQL data types to Java data types.
• Includes types like INTEGER, VARCHAR, DATE, BOOLEAN, etc.
• Used when setting parameters in PreparedStatement and retrieving data from ResultSet.
• Ensures compatibility between Java and database data types.

Executing SQL Queries

• Involves using Statement, PreparedStatement, or CallableStatement objects.
• executeQuery() method returns a ResultSet for SELECT queries.
• executeUpdate() method returns the number of rows affected for INSERT, UPDATE, or DELETE queries.
• Handle SQLException to manage potential errors during query execution.

ResultSetMetaData

• Provides information about the structure of a ResultSet.
• Includes column count, column names, and column types.
• Useful for dynamically processing query results.
• Obtained using the ResultSet.getMetaData() method.

Executing SQL Updates

• Modifying data in the database using SQL UPDATE, INSERT, or DELETE statements.
• Requires executing these statements using Statement, PreparedStatement, or CallableStatement objects.
• Ensure proper error handling and transaction management for data integrity.
• The executeUpdate method returns the number of rows affected.

Transaction Management

• Ensures data integrity by grouping multiple database operations into a single unit of work.
• Transactions are atomic, consistent, isolated, and durable (ACID properties).
• Methods include setAutoCommit(), commit(), and rollback().
• Proper transaction management is essential to maintain data consistency.