178 lines
10 KiB
HTML
178 lines
10 KiB
HTML
|
<?xml version="1.0" encoding="UTF-8"?>
|
||
|
|
<!DOCTYPE html
|
||
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
|
|
<html lang="en-us" xml:lang="en-us">
|
||
|
|
<head>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||
|
|
<meta name="security" content="public" />
|
||
|
|
<meta name="Robots" content="index,follow" />
|
||
|
|
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
|
||
|
|
<meta name="DC.Type" content="reference" />
|
||
|
|
<meta name="DC.Title" content="ResultSet class" />
|
||
|
|
<meta name="abstract" content="" />
|
||
|
|
<meta name="description" content="" />
|
||
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
|
||
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2006" />
|
||
|
|
<meta name="DC.Format" content="XHTML" />
|
||
|
|
<meta name="DC.Identifier" content="jdbcrs" />
|
||
|
|
<meta name="DC.Language" content="en-us" />
|
||
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
||
|
|
<!-- US Government Users Restricted Rights -->
|
||
|
|
<!-- Use, duplication or disclosure restricted by -->
|
||
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
||
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
||
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
||
|
|
<title>ResultSet class</title>
|
||
|
|
</head>
|
||
|
|
<body id="jdbcrs"><a name="jdbcrs"><!-- --></a>
|
||
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
||
|
|
<h1 class="topictitle1">ResultSet class</h1>
|
||
|
|
<div><p></p>
|
||
|
|
<div class="section"><p>You can use a <a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#NAVBAR_TOP">ResultSet</a> object to access a table of data that was generated
|
||
|
|
by running a query. The table rows are retrieved in sequence. Within a row,
|
||
|
|
column values can be accessed in any order.</p>
|
||
|
|
<p>The data stored in ResultSet
|
||
|
|
is retrieved by using the various <a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#GETASCIISTREAM(INT)">get</a> methods, depending on the type of data being retrieved.
|
||
|
|
The <a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#NEXT()">next()</a> method is used to move to the next row.</p>
|
||
|
|
<p>ResultSet
|
||
|
|
allows you to <a href="rzahhjdbcenhancev5r2.htm#rzahhjdbcenhancev5r2__callablestatementmethods">get
|
||
|
|
and update columns by name</a>, although using the column index results
|
||
|
|
improves performance.</p>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="jdbcrs__curmov"><a name="jdbcrs__curmov"><!-- --></a><h4 class="sectiontitle">Cursor movement</h4><p>A cursor, which is an
|
||
|
|
internal pointer, is used by a result set to point the row in the result
|
||
|
|
set that is being accessed by the Java™ program.</p>
|
||
|
|
<p>The performance of
|
||
|
|
the getRow() method has been improved. Before V5R2, using ResultSet.last(),
|
||
|
|
ResultSet.afterLast(), and ResultSet.absolute() with a negative value made
|
||
|
|
the current row number not available. The previous restrictions are lifted,
|
||
|
|
which makes the getRow() method fully functional.</p>
|
||
|
|
<p>JDBC 2.0 and later
|
||
|
|
JDBC specifications provide additional methods for accessing specific positions
|
||
|
|
within a database:</p>
|
||
|
|
|
||
|
|
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><thead align="left"><tr class="tablemainheaderbar"><th colspan="2" valign="top" id="d0e48">Scrollable cursor positions</th>
|
||
|
|
</tr>
|
||
|
|
</thead>
|
||
|
|
<tbody><tr><td valign="top" width="41.91919191919192%" headers="d0e48 "><p><a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#ABSOLUTE(INT)">absolute</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#AFTERLAST()">afterLast</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#BEFOREFIRST()">beforeFirst</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#FIRST()">first</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#GETROW()">getRow</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#ISAFTERLAST()">isAfterLast</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#ISBEFOREFIRST()">isBeforeFirst</a></p>
|
||
|
|
</td>
|
||
|
|
<td valign="top" width="58.080808080808076%" headers="d0e48 "><p><a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#ISFIRST()">isFirst</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#ISLAST()">isLast</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#LAST()">last</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#MOVETOCURRENTROW()">moveToCurrentRow</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#MOVETOINSERTROW()">moveToInsertRow</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#PREVIOUS()">previous</a> <br />
|
||
|
|
<a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#RELATIVE(INT)">relative</a></p>
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
</tbody>
|
||
|
|
</table>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="jdbcrs__scroll"><a name="jdbcrs__scroll"><!-- --></a><h4 class="sectiontitle">Scrolling capabilities</h4><p>If a result set
|
||
|
|
is created by executing a statement, you can move (scroll) backward (last-to-first)
|
||
|
|
or forward (first-to-last) through the rows in a table.</p>
|
||
|
|
<p>A result set
|
||
|
|
that supports this movement is called a scrollable result set. Scrollable
|
||
|
|
result sets also support absolute positioning. Absolute positioning allows
|
||
|
|
you to move directly to a row by specifying its position in the result set.</p>
|
||
|
|
<p>With
|
||
|
|
JDBC 2.0 and later JDBC specifications, you have two additional scrolling
|
||
|
|
capabilities available to use when working with the ResultSet class: scroll-insensitive
|
||
|
|
and scroll-sensitive result sets.</p>
|
||
|
|
<p>A scroll-insensitive result set is
|
||
|
|
not usually sensitive to changes that are made while it is open, while the
|
||
|
|
scroll-sensitive result set is sensitive to changes. </p>
|
||
|
|
<div class="note"><span class="notetitle">Note:</span> IBM<sup>®</sup> iSeries™ Server
|
||
|
|
only allows read-only access for scrollable insensitive cursors. IBM Toolbox for Java supports
|
||
|
|
a scroll-insensitive cursor if the result set concurrency is read-only. If
|
||
|
|
the result set type is specified as insensitive and the concurrency is specified
|
||
|
|
as updateable, the result set type changes to sensitive and issues a warning
|
||
|
|
to you.</div>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="jdbcrs__concur"><a name="jdbcrs__concur"><!-- --></a><h4 class="sectiontitle">Updateable result sets</h4><p>In your application,
|
||
|
|
you can use result sets that use either read-only concurrency (no updates
|
||
|
|
can be made to the data) or updateable concurrency (allows updates to the
|
||
|
|
data and uses database write locks to control access to the same data item
|
||
|
|
by different transactions). In an updateable result set, rows can be updated,
|
||
|
|
inserted, and deleted. Numerous update methods are available for you to use
|
||
|
|
in your program, for example:</p>
|
||
|
|
<ul><li><a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#UPDATEASCIISTREAM(INT, JAVA.IO.INPUTSTREAM, INT)">Update ASCII stream</a></li>
|
||
|
|
<li><a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#UPDATEBIGDECIMAL(INT, JAVA.MATH.BIGDECIMAL)">Update Big Decimal</a></li>
|
||
|
|
<li><a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#UPDATEBINARYSTREAM(INT, JAVA.IO.INPUTSTREAM, INT)">Update binary stream</a></li>
|
||
|
|
</ul>
|
||
|
|
<p>See <a href="javadoc/com/ibm/as400/access/AS400JDBCResultSet.html#METHOD_SUMMARY"> Method Summary</a> for a complete listing of the update
|
||
|
|
methods available through the ResultSet interface.</p>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="jdbcrs__updex"><a name="jdbcrs__updex"><!-- --></a><h4 class="sectiontitle">Example: Updatable result sets</h4><p>The following
|
||
|
|
example shows how to use a result set that allows updates to the data (update
|
||
|
|
concurrency) and allows changes to be made to the result set while it is open
|
||
|
|
(scroll sensitive).</p>
|
||
|
|
<pre> // Connect to the server.
|
||
|
|
Connection c = DriverManager.getConnection("jdbc:as400://mySystem");
|
||
|
|
|
||
|
|
// Create a Statement object. Set the result set
|
||
|
|
// concurrency to updatable.
|
||
|
|
Statement s = c.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
|
||
|
|
|
||
|
|
// Run a query. The result is placed
|
||
|
|
// in a ResultSet object.
|
||
|
|
ResultSet rs = s.executeQuery ("SELECT NAME,ID FROM MYLIBRARY.MYTABLE FOR UPDATE");
|
||
|
|
|
||
|
|
// Iterate through the rows of the ResultSet.
|
||
|
|
// As we read the row, we will update it with
|
||
|
|
// a new ID.
|
||
|
|
int newId = 0;
|
||
|
|
while (rs.next ())
|
||
|
|
{
|
||
|
|
|
||
|
|
// Get the values from the ResultSet.
|
||
|
|
// The first value is a string, and
|
||
|
|
// the second value is an integer.
|
||
|
|
String name = rs.getString("NAME");
|
||
|
|
int id = rs.getInt("ID");
|
||
|
|
|
||
|
|
System.out.println("Name = " + name);
|
||
|
|
System.out.println("Old id = " + id);
|
||
|
|
|
||
|
|
// Update the id with a new integer.
|
||
|
|
rs.updateInt("ID", ++newId);
|
||
|
|
|
||
|
|
// Send the updates to the server.
|
||
|
|
rs.updateRow ();
|
||
|
|
|
||
|
|
System.out.println("New id = " + newId);
|
||
|
|
}
|
||
|
|
|
||
|
|
// Close the Statement and the
|
||
|
|
// Connection.
|
||
|
|
s.close();
|
||
|
|
c.close();</pre>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="jdbcrs__resultsetmetadata"><a name="jdbcrs__resultsetmetadata"><!-- --></a><h4 class="sectiontitle">ResultSetMetaData</h4><p>The <a href="javadoc/com/ibm/as400/access/AS400JDBCResultSetMetaData.html#NAVBAR_TOP"> ResultSetMetaData</a> interface determines the types and
|
||
|
|
properties of the columns in a ResultSet.</p>
|
||
|
|
<p> When connecting to a server
|
||
|
|
running i5/OS™ V5R2
|
||
|
|
or later, using the <a href="jdbcproperties.htm#jdbcproperties__other">extended
|
||
|
|
metadata property</a> enables you to increase the accuracy of the following
|
||
|
|
ResultSetMetaData methods: </p>
|
||
|
|
<ul><li>getColumnLabel(int)</li>
|
||
|
|
<li>isReadOnly(int)</li>
|
||
|
|
<li>isSearchable(int)</li>
|
||
|
|
<li>isWriteable(int)</li>
|
||
|
|
</ul>
|
||
|
|
<p>Additionally, setting this property to true enables support for the
|
||
|
|
ResultSetMetaData.getSchemaName(int) method. Be aware that using the extended
|
||
|
|
metadata property may degrade performance because it requires retrieving more
|
||
|
|
information from the server. </p>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|