java.sql

What the JDBC^TM 4.0 API Includes

Versions

• The JDBC 3.0 API
• The JDBC 2.1 core API
• The JDBC 2.0 Optional Package API
  (Note that the JDBC 2.1 core API and the JDBC 2.0 Optional Package API together are referred to as the JDBC 2.0 API.)
• The JDBC 1.2 API
• The JDBC 1.0 API

Classes, interfaces, methods, fields, constructors, and exceptions have the following "since" tags that indicate when they were introduced into the Java platform. When these "since" tags are used in Javadoc^TM comments for the JDBC API, they indicate the following:

• Since 1.6 -- new in the JDBC 4.0 API and part of the Java SE platform, version 6
• Since 1.4 -- new in the JDBC 3.0 API and part of the J2SE platform, version 1.4
• Since 1.2 -- new in the JDBC 2.0 API and part of the J2SE platform, version 1.2
• Since 1.1 or no "since" tag -- in the original JDBC 1.0 API and part of the JDK^TM, version 1.1

NOTE: Many of the new features are optional; consequently, there is some variation in drivers and the features they support. Always check your driver's documentation to see whether it supports a feature before you try to use it.

NOTE: The class SQLPermission was added in the Java^TM 2 SDK, Standard Edition, version 1.3 release. This class is used to prevent unauthorized access to the logging stream associated with the DriverManager, which may contain information such as table names, column data, and so on.

What the java.sql Package Contains

• Making a connection with a database via the DriverManager facility
  • DriverManager class -- makes a connection with a driver
  • SQLPermission class -- provides permission when code running within a Security Manager, such as an applet, attempts to set up a logging stream through the DriverManager
  • Driver interface -- provides the API for registering and connecting drivers based on JDBC technology ("JDBC drivers"); generally used only by the DriverManager class
  • DriverPropertyInfo class -- provides properties for a JDBC driver; not used by the general user
• Sending SQL statements to a database
  • Statement -- used to send basic SQL statements
  • PreparedStatement -- used to send prepared statements or basic SQL statements (derived from Statement)
  • CallableStatement -- used to call database stored procedures (derived from PreparedStatement)
  • Connection interface -- provides methods for creating statements and managing connections and their properties
  • Savepoint -- provides savepoints in a transaction
• Retrieving and updating the results of a query
  • ResultSet interface
• Standard mappings for SQL types to classes and interfaces in the Java programming language
  • Array interface -- mapping for SQL ARRAY
  • Blob interface -- mapping for SQL BLOB
  • Clob interface -- mapping for SQL CLOB
  • Date class -- mapping for SQL DATE
  • NClob interface -- mapping for SQL NCLOB
  • Ref interface -- mapping for SQL REF
  • RowId interface -- mapping for SQL ROWID
  • Struct interface -- mapping for SQL STRUCT
  • SQLXML interface -- mapping for SQL XML
  • Time class -- mapping for SQL TIME
  • Timestamp class -- mapping for SQL TIMESTAMP
  • Types class -- provides constants for SQL types
• Custom mapping an SQL user-defined type (UDT) to a class in the Java programming language
  • SQLData interface -- specifies the mapping of a UDT to an instance of this class
  • SQLInput interface -- provides methods for reading UDT attributes from a stream
  • SQLOutput interface -- provides methods for writing UDT attributes back to a stream
• Metadata
  • DatabaseMetaData interface -- provides information about the database
  • ResultSetMetaData interface -- provides information about the columns of a ResultSet object
  • ParameterMetaData interface -- provides information about the parameters to PreparedStatement commands
• Exceptions
  • SQLException -- thrown by most methods when there is a problem accessing data and by some methods for other reasons
  • SQLWarning -- thrown to indicate a warning
  • DataTruncation -- thrown to indicate that data may have been truncated
  • BatchUpdateException -- thrown to indicate that not all commands in a batch update executed successfully

java.sql and javax.sql Features Introduced in the JDBC 4.0 API

• auto java.sql.Driver discovery -- no longer need to load a java.sql.Driver class via Class.forName
• National Character Set support added
• Support added for the SQL:2003 XML data type
• SQLException enhancements -- Added support for cause chaining; New SQLExceptions added for common SQLState class value codes
• Enhanced Blob/Clob functionality -- Support provided to create and free a Blob/Clob instance as well as additional methods added to improve accessiblity
• Support added for accessing a SQL ROWID
• Support added to allow a JDBC application to access an instance of a JDBC resource that has been wrapped by a vendor, usually in an application server or connection pooling environment.
• Availability to be notfied when a PreparedStatement that is associated with a PooledConnection has been closed or the driver determines is invalid

java.sql and javax.sql Features Introduced in the JDBC 3.0 API

• Pooled statements -- reuse of statements associated with a pooled connection
• Savepoints -- allow a transaction to be rolled back to a designated savepoint
• Properties defined for ConnectionPoolDataSource -- specify how connections are to be pooled
• Metadata for parameters of a PreparedStatement object
• Ability to retrieve values from automatically generated columns
• Ability to have multiple ResultSet objects returned from CallableStatement objects open at the same time
• Ability to identify parameters to CallableStatement objects by name as well as by index
• ResultSet holdability -- ability to specify whether cursors should be held open or closed at the end of a transaction
• Ability to retrieve and update the SQL structured type instance that a Ref object references
• Ability to programmatically update BLOB, CLOB, ARRAY, and REF values.
• Addition of the java.sql.Types.DATALINK data type -- allows JDBC drivers access to objects stored outside a data source
• Addition of metadata for retrieving SQL type hierarchies

java.sql Features Introduced in the JDBC 2.1 Core API

• Scrollable result sets--using new methods in the ResultSet interface that allow the cursor to be moved to a particular row or to a position relative to its current position
• Batch updates
• Programmatic updates--using ResultSet updater methods
• New data types--interfaces mapping the SQL3 data types
• Custom mapping of user-defined types (UDTs)
• Miscellaneous features, including performance hints, the use of character streams, full precision for java.math.BigDecimal values, additional security, and support for time zones in date, time, and timestamp values.

javax.sql Features Introduced in the JDBC 2.0 Optional Package API

• The DataSource interface as a means of making a connection. The Java Naming and Directory Interface^TM (JNDI) is used for registering a DataSource object with a naming service and also for retrieving it.
• Pooled connections -- allowing connections to be used and reused
• Distributed transactions -- allowing a transaction to span diverse DBMS servers
• RowSet technology -- providing a convenient means of handling and passing data

Custom Mapping of UDTs

1. Defining the SQL structured type or DISTINCT type in SQL
2. Defining the class in the Java programming language to which the SQL UDT will be mapped. This class must implement the SQLData interface.
3. Making an entry in a Connection object's type map that contains two things:
   • the fully-qualified SQL name of the UDT
   • the Class object for the class that implements the SQLData interface

When these are in place for a UDT, calling the methods ResultSet.getObject or CallableStatement.getObject on that UDT will automatically retrieve the custom mapping for it. Also, the PreparedStatement.setObject method will automatically map the object back to its SQL type to store it in the data source.

Package Specification

• Specification of the JDBC 4.0 API

Related Documentation

• Getting Started--overviews of the major interfaces

• Chapters on the JDBC API--from the online version of The Java Tutorial Continued

• JDBC^TMAPI Tutorial and Reference, Third Edition-- a complete reference and tutorial for the JDBC 3.0 API

@since 1.1

A connection (session) with a specific database.

This interface is implemented by driver vendors to let users know the capabilities of a Database Management System (DBMS) in combination with the driver based on JDBC^TM technology ("JDBC driver") that is used with it.

A thin wrapper around a millisecond value that allows JDBC to identify this as an SQL DATE value.

The Java SQL framework allows for multiple database drivers.

Each driver should supply a class that implements the Driver interface.

The DriverManager will try to load as many drivers as it can find and then for any given connection request, it will ask each driver in turn to try to connect to the target URL.

It is strongly recommended that each Driver class should be small and standalone so that the Driver class can be loaded and queried without bringing in vast quantities of supporting code.

When a Driver class is loaded, it should create an instance of itself and register it with the DriverManager.

The basic service for managing a set of JDBC drivers.
NOTE: The DataSource interface, new in the JDBC 2.0 API, provides another way to connect to a data source. The use of a DataSource object is the preferred means of connecting to a data source.

Driver properties for making a connection.

The NClob interface extends the Clob interface which provides provides methods for getting the length of an SQL NCLOB value, for materializing a NCLOB value on the client, and for searching for a substring or NCLOB object within a NCLOB value.

A SQL statement is precompiled and stored in a PreparedStatement object.

SQL REF values are stored in a table that contains instances of a referenceable SQL structured type, and each REF value is a unique identifier for one instance in that table.

An exception that provides information on a database access error or other errors.

Each SQLException provides several kinds of information:

• a string describing the error.

The subclass of SQLException thrown for the SQLState class value '08', representing that the connection operation that failed will not succeed when the operation is retried without the cause of the failure being corrected.

A SQLPermission object contains a name (also referred to as a "target name") but no actions list; there is either a named permission or there is not. The target name is the name of the permission (see below).

The subclass of SQLException thrown when the timeout specified by Statement has expired.

An exception that provides information on database access warnings.

The object used for executing a static SQL statement and returning the results it produces.

By default, only one ResultSet object per Statement object can be open at the same time.

The standard mapping in the Java programming language for an SQL structured type.

A thin wrapper around the java.util.Date class that allows the JDBC API to identify this as an SQL TIME value.

A thin wrapper around java.util.Date that allows the JDBC API to identify this as an SQL TIMESTAMP value. It adds the ability to hold the SQL TIMESTAMP fractional seconds value, by allowing the specification of fractional seconds to a precision of nanoseconds. A Timestamp also provides formatting and parsing operations to support the JDBC escape syntax for timestamp values.

The precision of a Timestamp object is calculated to be either:

• 19 , which is the number of characters in yyyy-mm-dd hh:mm:ss
• 20 + s , which is the number of characters in the yyyy-mm-dd hh:mm:ss.[fff...] and s represents the scale of the given Timestamp, its fractional seconds precision.

Note: This type is a composite of a java.util.Date and a separate nanoseconds value.

The class that defines the constants that are used to identify generic SQL types, called JDBC types.

The wrapper pattern is employed by many JDBC driver implementations to provide extensions beyond the traditional JDBC API that are specific to a data source.