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Package java.sql

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          Description

Package java.sql Description

Provides the API for accessing and processing data stored in a data source (usually a relational database) using the Java programming language. This API includes a framework whereby differentdrivers can be installed dynamically to access different data sources.Although the JDBC API is mainly geared to passing SQL statements to a database, it provides for reading andwriting data from any data source with a tabular format.The reader/writer facility, available through thejavax.sql.RowSet group of interfaces, can be customized touse and update data from a spread sheet, flat file, or any other tabular data source.

What the JDBC 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 inJavadoc 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, 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 beforeyou try to use it.

NOTE: The classSQLPermission was added in theJava 2 SDK, Standard Edition, version 1.3 release. This class is used to prevent unauthorizedaccess to the logging stream associated with theDriverManager,which may contain information such as table names, column data, and so on.

What thejava.sql Package Contains

• Making a connection with a database via theDriverManager 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 theDriverManager
  • Driver interface -- provides the API for registering and connecting drivers based on JDBC technology ("JDBC drivers"); generally used only by theDriverManager 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 fromStatement)
  • CallableStatement -- used to call database stored procedures (derived fromPreparedStatement)
  • 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 SQLARRAY
  • Blob interface -- mapping for SQLBLOB
  • Clob interface -- mapping for SQLCLOB
  • Date class -- mapping for SQLDATE
  • NClob interface -- mapping for SQLNCLOB
  • Ref interface -- mapping for SQLREF
  • RowId interface -- mapping for SQLROWID
  • Struct interface -- mapping for SQLSTRUCT
  • SQLXML interface -- mapping for SQLXML
  • Time class -- mapping for SQLTIME
  • Timestamp class -- mapping for SQLTIMESTAMP
  • 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 aResultSet object
  • ParameterMetaData interface -- provides information about the parameters toPreparedStatement 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 andjavax.sql Features Introduced in the JDBC 4.0 API

• auto java.sql.Driver discovery -- no longer need to load ajava.sql.Driver class viaClass.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 aPreparedStatement that is associated with aPooledConnection has been closed or the driver determines is invalid

java.sql andjavax.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 forConnectionPoolDataSource -- specify how connections are to be pooled
• Metadata for parameters of aPreparedStatement object
• Ability to retrieve values from automatically generated columns
• Ability to have multipleResultSet objects returned fromCallableStatement objects open at the same time
• Ability to identify parameters toCallableStatement 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 aRef object references
• Ability to programmatically updateBLOB,CLOB,ARRAY, andREF values.
• Addition of thejava.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 theResultSet 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--usingResultSet 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 forjava.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 OptionalPackage API

• TheDataSource interface as a means of making a connection. The Java Naming and Directory Interface (JNDI) is used for registering aDataSource 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 orDISTINCT type in SQL
2. Defining the class in the Java programming language to which the SQL UDT will be mapped. This class must implement theSQLData interface.
3. Making an entry in aConnection object's type map that contains two things:
   • the fully-qualified SQL name of the UDT
   • theClass object for the class that implements theSQLData interface

When these are in place for a UDT, calling the methodsResultSet.getObject orCallableStatement.getObject on that UDT will automatically retrieve the custom mapping for it. Also, thePreparedStatement.setObject method will automatically map theobject 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 ofThe Java Tutorial Continued

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

Since:

1.1