Java Programming - MCQ Practice Questions

PreparedStatement offers faster execution due to precompilation and prevents SQL injection through parameterized queries using placeholders (?).

The next() method moves the ResultSet cursor to the next row and returns true if a row exists, false if no more rows. It's essential for iterating through results.

Connection pooling maintains a pool of reusable database connections to improve performance and reduce overhead of creating new connections repeatedly.

DriverManager.getConnection() is the standard method that takes URL, username, and password to establish a connection to the database.

setAutoCommit(false) disables automatic commit, allowing multiple statements to be part of single transaction. Manual commit() or rollback() must be called.

This is vulnerable to SQL injection as user input is directly concatenated. Using PreparedStatement with parameters prevents this: "SELECT * FROM users WHERE id=?"

addBatch() adds SQL command to batch, executeBatch() executes all batched commands at once, improving performance significantly for multiple operations.

execute() returns boolean (true if ResultSet available), executeQuery() returns ResultSet for SELECT, executeUpdate() returns row count for INSERT/UPDATE/DELETE.

CallableStatement is used to invoke stored procedures and functions. It extends PreparedStatement and supports IN, OUT, and INOUT parameters.

TYPE_SCROLL_INSENSITIVE creates scrollable ResultSet (can move forward/backward) but changes made to database after ResultSet creation are not reflected.

Resources should be closed in reverse order of creation (ResultSet → Statement → Connection), or preferably using try-with-resources which auto-closes resources.

Type 4 drivers (thin drivers) are pure Java drivers that communicate directly with the database using the database native protocol. They are platform-independent and do not require native code.

The correct method is getInt(int columnIndex) which retrieves an integer value from the ResultSet at the specified column index (1-based indexing).

ResultSet interface represents the result set of a query. It contains the data returned from a database query and provides methods to access and traverse through the rows.

PreparedStatement provides both parameterized queries (preventing SQL injection) and precompilation of SQL statements, resulting in better security and performance compared to Statement.

Class.forName() is used to load the JDBC driver class dynamically and register it with the DriverManager. For example: Class.forName("com.mysql.cj.jdbc.Driver");

SQLIntegrityConstraintViolationException is a specific subclass of SQLException that is thrown when integrity constraint violations occur, such as unique constraint violations.

The try-with-resources statement automatically closes resources implementing AutoCloseable. Since Connection implements AutoCloseable, it will be automatically closed.

The getDatabaseMetaData() method is called on a Connection object to retrieve DatabaseMetaData information about the database, such as table names, column information, etc.

The absolute(int row) method moves the cursor to the specified row number (1-based indexing). absolute(5) moves the cursor directly to row 5.