src/java.sql/share/classes/java/sql/package.html
author erikj
Tue, 12 Sep 2017 19:03:39 +0200
changeset 47216 71c04702a3d5
parent 45008 jdk/src/java.sql/share/classes/java/sql/package.html@c5266a7717cf
permissions -rw-r--r--
8187443: Forest Consolidation: Move files to unified layout Reviewed-by: darcy, ihse

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

<h2>What the JDBC&trade; 4.3 API Includes</h2>
The JDBC&trade; 4.3 API includes both
the <code>java.sql</code> package, referred to as the JDBC core API,
and the <code>javax.sql</code> package, referred to as the JDBC Optional
Package API. This complete JDBC API
is included in the Java&trade; Standard Edition (Java SE&trade;), version 7.
The <code>javax.sql</code> package extends the functionality of the JDBC API
from a client-side API to a server-side API, and it is an essential part
of the Java&trade;  Enterprise Edition
(Java EE&trade;) technology.

<h2>Versions</h2>
The JDBC 4.3 API incorporates all of the previous JDBC API versions:
<UL>
    <LI> The JDBC 4.2 API</li>
    <LI> The JDBC 4.1 API</li>
    <LI> The JDBC 4.0 API</li>
    <LI> The JDBC 3.0 API</li>
    <LI> The JDBC 2.1 core API</li>
 <LI> The JDBC 2.0 Optional Package API<br>
      (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.)</li>
 <LI> The JDBC 1.2 API</li>
 <LI> The JDBC 1.0 API</li>
</UL>
<P>
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&trade; comments for the JDBC API,
they indicate the following:
<UL>
    <LI>Since 9 -- new in the JDBC 4.3 API and part of the Java SE platform,
        version 9</li>
     <LI>Since 1.8 -- new in the JDBC 4.2 API and part of the Java SE platform,
        version 8</li>
 <LI>Since 1.7 -- new in the JDBC 4.1 API and part of the Java SE platform,
     version 7</li>
<LI>Since 1.6 -- new in the JDBC 4.0 API and part of the Java SE platform,
    version 6</li>
 <LI>Since 1.4 -- new in the JDBC 3.0 API and part of the J2SE platform,
     version 1.4</li>
 <LI>Since 1.2 -- new in the JDBC 2.0 API and part of the J2SE platform,
     version 1.2</li>
 <LI>Since 1.1 or no "since" tag -- in the original JDBC 1.0 API and part of
     the JDK&trade;, version 1.1</li>
</UL>
<P>
<b>NOTE:</b> 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.
<P>
<b>NOTE:</b> The class <code>SQLPermission</code> was added in the
Java&trade; 2 SDK, Standard Edition,
version 1.3 release. This class is used to prevent unauthorized
access to the logging stream associated with the <code>DriverManager</code>,
which may contain information such as table names, column data, and so on.

<h2>What the <code>java.sql</code> Package Contains</h2>
The <code>java.sql</code> package contains API for the following:
<UL>
  <LI>Making a connection with a database via the <code>DriverManager</code> facility
  <UL>
	 <LI><code>DriverManager</code> class -- makes a connection with a driver
	 <LI><code>SQLPermission</code> class -- provides permission when code
                  running within a Security Manager, such as an applet,
                  attempts to set up a logging stream through the
                  <code>DriverManager</code>
	 <LI><code>Driver</code> interface -- provides the API for registering
             and connecting drivers based on JDBC technology ("JDBC drivers");
             generally used only by the <code>DriverManager</code> class
	 <LI><code>DriverPropertyInfo</code> class -- provides properties for a
             JDBC driver; not used by the general user
  </UL>
  <LI>Sending SQL statements to a database
  <UL>
	 <LI><code>Statement</code> --  used to send basic SQL statements
	 <LI><code>PreparedStatement</code> --  used to send prepared statements or
              basic SQL statements (derived from <code>Statement</code>)
	 <LI><code>CallableStatement</code> --  used to call database stored
              procedures (derived from <code>PreparedStatement</code>)
	 <LI><code>Connection</code> interface --  provides methods for creating
             statements and managing connections and their properties
	 <LI><code>Savepoint</code> --  provides savepoints in a transaction

  </UL>
  <LI>Retrieving and updating the results of a query
  <UL>
	 <LI><code>ResultSet</code> interface
  </UL>
  <LI>Standard mappings for SQL types to classes and interfaces in the
      Java programming language
  <UL>
	 <LI><code>Array</code> interface -- mapping for SQL <code>ARRAY</code>
	 <LI><code>Blob</code> interface -- mapping for SQL <code>BLOB</code>
	 <LI><code>Clob</code> interface -- mapping for SQL <code>CLOB</code>
	 <LI><code>Date</code> class -- mapping for SQL <code>DATE</code>
	  <LI><code>NClob</code> interface -- mapping for SQL <code>NCLOB</code>
	 <LI><code>Ref</code> interface -- mapping for SQL <code>REF</code>
	  <LI><code>RowId</code> interface -- mapping for SQL <code>ROWID</code>
	 <LI><code>Struct</code> interface -- mapping for SQL <code>STRUCT</code>
	  <LI><code>SQLXML</code> interface -- mapping for SQL <code>XML</code>
	 <LI><code>Time</code> class -- mapping for SQL <code>TIME</code>
	 <LI><code>Timestamp</code> class -- mapping for SQL <code>TIMESTAMP</code>
	 <LI><code>Types</code> class -- provides constants for SQL types
  </UL>
  <LI>Custom mapping an SQL user-defined type (UDT) to a class in the
	  Java programming language
  <UL>
	 <LI><code>SQLData</code> interface -- specifies the mapping of
              a UDT to an instance of this class
	 <LI><code>SQLInput</code> interface -- provides methods for reading
              UDT attributes from a stream
	 <LI><code>SQLOutput</code> interface -- provides methods for writing
              UDT attributes back to a stream
  </UL>
  <LI>Metadata
  <UL>
	 <LI><code>DatabaseMetaData</code> interface -- provides information
              about the database
	 <LI><code>ResultSetMetaData</code> interface -- provides information
              about the columns of a <code>ResultSet</code> object
	 <LI><code>ParameterMetaData</code> interface -- provides information
              about the parameters to <code>PreparedStatement</code> commands
  </UL>
  <LI>Exceptions
	<UL>
	  <LI><code>SQLException</code> -- thrown by most methods when there
		 is a problem accessing data and by some methods for other reasons
	  <LI><code>SQLWarning</code> -- thrown to indicate a warning
	  <LI><code>DataTruncation</code> -- thrown to indicate that data may have
     	  been truncated
	  <LI><code>BatchUpdateException</code> -- thrown to indicate that not all
		 commands in a batch update executed successfully
	</UL>
</UL>

    <h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 4.3 API</h3>
<UL>
    <LI>Added <code>Sharding</code> support</LI>
    <LI>Enhanced <code>Connection</code> to be able to provide hints
        to the driver that a request, an independent unit of work,
        is beginning or ending</LI>
    <LI>Enhanced <code>DatabaseMetaData</code> to determine if Sharding is
    supported</LI>
    <LI>Added the method <code>drivers</code> to <code>DriverManager</code> 
            to return a Stream of the currently loaded and
            available JDBC drivers</LI>
    <LI>Added support to <code>Statement</code> for enquoting literals
    and simple identifiers</LI>
    <LI>Clarified the Java SE version that methods were deprecated</LI>
</UL>

    <h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 4.2 API</h3>
<UL>
    <LI>Added <code>JDBCType</code>  enum and <code>SQLType</code> interface</li>
    <LI>Support for <code>REF CURSORS</code> in <code>CallableStatement</code>
    </LI>
    <LI><code>DatabaseMetaData</code> methods to return maximum Logical LOB size
        and if Ref Cursors are supported</LI>
    <LI>Added support for large update counts</LI>

</UL>

    <h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 4.1 API</h3>
<UL>
    <LI>Allow <code>Connection</code>,
        <code>ResultSet</code> and <code>Statement</code> objects to be
        used with the try-with-resources statement</LI>
    <LI>Support added to <code>CallableStatement</code> and
        <code>ResultSet</code> to specify the Java type to convert to via the
        <code>getObject</code> method</LI>
    <LI><code>DatabaseMetaData</code> methods to return PseudoColumns and if a
        generated key is always returned</LI>
    <LI>Added support to <code>Connection</code> to specify a database schema,
    abort and timeout a physical connection.</LI>
    <LI>Added support to close a <code>Statement</code> object when its dependent
    objects have been closed</LI>
    <LI>Support for obtaining the parent logger for a <code>Driver</code>,
     <code>DataSource</code>, <code>ConnectionPoolDataSource</code> and
     <code>XADataSource</code></LI>

</UL>
<h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 4.0 API</h3>
<UL>
  <LI>auto java.sql.Driver discovery -- no longer need to load a
<code>java.sql.Driver</code> class via <code>Class.forName</code>
 <LI>National Character Set support added
 <li>Support added for the SQL:2003 XML data type
 <lI>SQLException enhancements -- Added support for cause chaining; New SQLExceptions
 added for common SQLState class value codes
 <li>Enhanced Blob/Clob functionality -- Support provided to create and free a Blob/Clob instance
 as well as additional methods added to improve accessibility
 <li>Support added for accessing a SQL ROWID
 <li>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.
 <li>Availability to be notified when a <code>PreparedStatement</code> that is associated
 with a <code>PooledConnection</code> has been closed or the driver determines is invalid


</UL>


<h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 3.0 API</h3>
<UL>
  <LI>Pooled statements -- reuse of statements associated with a pooled
       connection
  <LI>Savepoints -- allow a transaction to be rolled back to a designated
      savepoint
  <LI>Properties defined for <code>ConnectionPoolDataSource</code> -- specify
      how connections are to be pooled
  <LI>Metadata for parameters of a <code>PreparedStatement</code> object
  <LI>Ability to retrieve values from automatically generated columns
  <LI>Ability to have multiple <code>ResultSet</code> objects
       returned from <code>CallableStatement</code> objects open at the
      same time
  <LI>Ability to identify parameters to <code>CallableStatement</code>
      objects by name as well as by index
  <LI><code>ResultSet</code> holdability -- ability to specify whether cursors
      should be held open or closed at the end of a transaction
  <LI>Ability to retrieve and update the SQL structured type instance that a
      <code>Ref</code> object references
  <LI>Ability to programmatically update <code>BLOB</code>,
      <code>CLOB</code>, <code>ARRAY</code>, and <code>REF</code> values.
  <LI>Addition of the <code>java.sql.Types.DATALINK</code> data type --
      allows JDBC drivers access to objects stored outside a data source
  <LI>Addition of metadata for retrieving SQL type hierarchies
</UL>

<h3><code>java.sql</code> Features Introduced in the JDBC 2.1 Core API</h3>
<UL>
  <LI>Scrollable result sets--using new methods in the <code>ResultSet</code>
	  interface that allow the cursor to be moved to a particular row or to a
	  position relative to its current position
  <LI>Batch updates
  <LI>Programmatic updates--using <code>ResultSet</code> updater methods
  <LI>New data types--interfaces mapping the SQL3 data types
  <LI>Custom mapping of user-defined types (UDTs)
  <LI>Miscellaneous features, including performance hints, the use of character
	  streams, full precision for <code>java.math.BigDecimal</code> values,
	  additional security, and
	  support for time zones in date, time, and timestamp values.
</UL>

<h3><code>javax.sql</code> Features Introduced in the JDBC 2.0 Optional
Package API</h3>
<UL>
  <LI>The <code>DataSource</code> interface as a means of making a connection.  The
      Java Naming and Directory Interface&trade;
      (JNDI) is used for registering a <code>DataSource</code> object with a
      naming service and also for  retrieving it.
  <LI>Pooled connections -- allowing connections to be used and reused
  <LI>Distributed transactions -- allowing a transaction to span diverse
      DBMS servers
  <LI><code>RowSet</code> technology -- providing a convenient means of
       handling and passing data
</UL>


<h3>Custom Mapping of UDTs</h3>
A user-defined type (UDT) defined in SQL can be mapped to a class in the Java
programming language. An SQL structured type or an SQL <code>DISTINCT</code>
type are the UDTs that may be custom mapped.  The following three
steps set up a custom mapping:
<ol>
  <li>Defining the SQL structured type or <code>DISTINCT</code> type in SQL
  <li>Defining the class in the Java programming language to which the
	  SQL UDT will be mapped.  This class must implement the
	  <code>SQLData</code> interface.
  <li>Making an entry in a <code>Connection</code> object's type map
      that contains two things:
   <ul>
       <li>the fully-qualified SQL name of the UDT
       <li>the <code>Class</code> object for the class that implements the
           <code>SQLData</code> interface
   </ul>
</ol>
<p>
When these are in place for a UDT, calling the methods
<code>ResultSet.getObject</code> or <code>CallableStatement.getObject</code>
on that UDT will automatically retrieve the custom mapping for it. Also, the
<code>PreparedStatement.setObject</code> method will automatically map the
object back to its SQL type to store it in the data source.

<h2>Package Specification</h2>

<ul>
  <li><a href="https://jcp.org/en/jsr/detail?id=221">JDBC 4.3 Specification</a>
</ul>

<h2>Related Documentation</h2>

<ul>
  <li><a href="http://docs.oracle.com/javase/tutorial/jdbc/basics/index.html">
          Lesson:JDBC Basics(The Javaxx Tutorials &gt; JDBC&trade; Database Access)</a>

 <li><a href="http://www.oracle.com/technetwork/java/index-142838.html">
          <i>JDBC&trade; API Tutorial and Reference, Third Edition</i></a>
</ul>

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