Java Programming

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

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

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

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

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

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

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

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

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

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.