199 lines
8.3 KiB
HTML
199 lines
8.3 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Example: Using JDBC classes to create and populate a table (part 2 of 2)" />
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<meta name="abstract" content="" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Example: Using JDBC classes to create and populate a table (part 2
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of 2)</title>
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</head>
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<body id="jdbcex2"><a name="jdbcex2"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Example: Using JDBC classes to create and populate a table (part 2
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of 2)</h1>
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<div><p></p>
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<div class="section"><p>[ <a href="jdbcex1.htm#jdbcex1">Previous part</a> ]</p>
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<p>Use
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the following as an example for your program.</p>
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<div class="note"><span class="notetitle">Note:</span> Read the <a href="codedisclaimer.htm#codedisclaimer">Code
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example disclaimer</a> for important legal information.</div>
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<pre>//////////////////////////////////////////////////////////////////////////////////
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//
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// JDBCQuery example. This program uses the IBM Toolbox for Java JDBC driver to
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// query a table and output its contents.
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//
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// Command syntax:
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// JDBCQuery system collectionName tableName
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//
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// For example,
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// JDBCQuery MySystem qiws qcustcdt
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//
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// This source is an example of IBM Toolbox for Java JDBC driver.
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//
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//////////////////////////////////////////////////////////////////////////////////
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import java.sql.*;
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public class JDBCQuery
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{
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// Format a string so that it has the specified width.
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private static String format (String s, int width)
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{
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String formattedString;
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// The string is shorter than specified width,
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// so we need to pad with blanks.
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if (s.length() < width) {
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StringBuffer buffer = new StringBuffer (s);
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for (int i = s.length(); i < width; ++i)
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buffer.append (" ");
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formattedString = buffer.toString();
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}
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// Otherwise, we need to truncate the string.
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else
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formattedString = s.substring (0, width);
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return formattedString;
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}
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public static void main (String[] parameters)
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{
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// Check the input parameters.
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if (parameters.length != 3) {
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System.out.println("");
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System.out.println("Usage:");
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System.out.println("");
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System.out.println(" JDBCQuery system collectionName tableName");
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System.out.println("");
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System.out.println("");
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System.out.println("For example:");
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System.out.println("");
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System.out.println("");
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System.out.println(" JDBCQuery mySystem qiws qcustcdt");
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System.out.println("");
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return;
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}
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String system = parameters[0];
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String collectionName = parameters[1];
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String tableName = parameters[2];
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Connection connection = null;
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try {
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DriverManager.registerDriver(new com.ibm.as400.access.AS400JDBCDriver()); <a href="#jdbcex2__dup0030">Note 1 </a>
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// Get a connection to the database. Since we do not
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// provide a user id or password, a prompt will appear.
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connection = DriverManager.getConnection ("jdbc:as400://" + system);
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DatabaseMetaData dmd = connection.getMetaData (); <a href="#jdbcex2__dup0031">Note 2 </a>
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// Execute the query.
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Statement select = connection.createStatement ();
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ResultSet rs = select.executeQuery ("SELECT * FROM "
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+ collectionName + dmd.getCatalogSeparator() + tableName); <a href="#jdbcex2__dup0032">Note 3 </a>
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// Get information about the result set. Set the column
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// width to whichever is longer: the length of the label
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// or the length of the data.
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ResultSetMetaData rsmd = rs.getMetaData ();
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int columnCount = rsmd.getColumnCount (); <a href="#jdbcex2__dup0033">Note 4 </a>
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String[] columnLabels = new String[columnCount];
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int[] columnWidths = new int[columnCount];
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for (int i = 1; i <= columnCount; ++i) {
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columnLabels[i-1] = rsmd.getColumnLabel (i);
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columnWidths[i-1] = Math.max (columnLabels[i-1].length(),
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rsmd.getColumnDisplaySize (i)); <a href="#jdbcex2__dup0034">Note 5 </a>
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}
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// Output the column headings.
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for (int i = 1; i <= columnCount; ++i) {
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System.out.print (format (rsmd.getColumnLabel(i), columnWidths[i-1]));
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System.out.print (" ");
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}
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System.out.println ();
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// Output a dashed line.
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StringBuffer dashedLine;
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for (int i = 1; i <= columnCount; ++i) {
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for (int j = 1; j <= columnWidths[i-1]; ++j)
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System.out.print ("-");
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System.out.print (" ");
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}
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System.out.println ();
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// Iterate throught the rows in the result set and output
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// the columns for each row.
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while (rs.next ()) {
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for (int i = 1; i <= columnCount; ++i) {
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String value = rs.getString (i);
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if (rs.wasNull ())
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value = "<null>"; <a href="#jdbcex2__dup0035">Note 6 </a>
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System.out.print (format (value, columnWidths[i-1]));
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System.out.print (" ");
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}
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System.out.println ();
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}
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}
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catch (Exception e) {
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System.out.println ();
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System.out.println ("ERROR: " + e.getMessage());
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}
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finally {
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// Clean up.
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try {
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if (connection != null)
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connection.close ();
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}
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catch (SQLException e) {
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// Ignore.
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}
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}
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System.exit (0);
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}
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}</pre>
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</div>
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<div class="section"><ol><li id="jdbcex2__dup0030"><a name="jdbcex2__dup0030"><!-- --></a>This line loads the IBM<sup>®</sup> Toolbox for Java™ JDBC driver. A JDBC driver mediates
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between JDBC and the database with which you are working.</li>
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<li id="jdbcex2__dup0031"><a name="jdbcex2__dup0031"><!-- --></a>This line retrieves the connection's meta data, an object
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that describes many of the characteristics of the database.</li>
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<li id="jdbcex2__dup0032"><a name="jdbcex2__dup0032"><!-- --></a>This statement executes the query on the specified table.</li>
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<li id="jdbcex2__dup0033"><a name="jdbcex2__dup0033"><!-- --></a>These lines retrieve information about the table.</li>
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<li id="jdbcex2__dup0034"><a name="jdbcex2__dup0034"><!-- --></a>These lines set the column width to either the length of
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the label or the length of the data, whichever is longer.</li>
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<li id="jdbcex2__dup0035"><a name="jdbcex2__dup0035"><!-- --></a>This block of code iterates through all of the rows in the
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table and displays the contents of each column in each row.</li>
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</ol>
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<p>[ <a href="jdbcex1.htm#jdbcex1">Previous part</a> ]</p>
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</div>
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</div>
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</body>
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</html> |