javasql

Javasql, also known as Java SQL, refers to the set of APIs in the Java Platform that enables Java applications to interact with relational databases. It is part of the Java Standard Edition and the java.sql package and related interfaces. JDBC provides a framework for connecting to a database, sending SQL statements, and processing results in a database-agnostic way, while allowing database-specific features through vendor libraries.

Core components include the Driver, DriverManager, DataSource, Connection, Statement, PreparedStatement, CallableStatement, ResultSet, and metadata interfaces such as DatabaseMetaData and ResultSetMetaData. Exceptions are represented by SQLException. The API supports transactions, batch updates, and streaming results, and it can handle both static and parameterized queries.

Drivers and architecture: JDBC drivers are implemented by database vendors and loaded by the DriverManager or via a DataSource. There are four driver types (Type 1 through Type 4). Type 4 is a pure Java driver that talks directly to the database; Type 1 is a JDBC-ODBC bridge; Type 2 uses native code libraries; Type 3 is a network middleware driver. Over time, most environments rely on Type 4 drivers for portability.

Typical usage: loading the driver is usually automatic with modern JVMs. A connection is obtained with DriverManager.getConnection or a DataSource. A Statement or PreparedStatement is created to execute SQL; a ResultSet processes results. Resources should be closed promptly, preferably with try-with-resources. Prepared statements help prevent SQL injection and facilitate parameter binding.

Metadata and portability: DatabaseMetaData reports capabilities and features of the connected database. JDBC provides a standard API across databases, but vendor-specific features may require extensions. JDBC remains a core part of Java SE for database access.