Example: Using JDBC classes to create and populate a table (part 1 of 2)

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Use the following as an example for your program.

//////////////////////////////////////////////////////////////////////////////////
//
// JDBCPopulate example.  This program uses the IBM Toolbox for Java JDBC driver 
// to create and populate a table.
//
// Command syntax:
//    JDBCPopulate system collectionName tableName
//
// For example,
//    JDBCPopulate MySystem MyLibrary MyTable
//
// This source is an example of IBM Toolbox for Java JDBC driver.
//
//////////////////////////////////////////////////////////////////////////////////

import java.sql.*;

public class JDBCPopulate
{

    private static final String words[]
        = { "One",      "Two",      "Three",    "Four",     "Five",
            "Six",      "Seven",    "Eight",    "Nine",     "Ten",
            "Eleven",   "Twelve",   "Thirteen", "Fourteen", "Fifteen",
            "Sixteen",  "Seventeen","Eighteen", "Nineteen", "Twenty" };

    public static void main (String[] parameters)
    {

        if (parameters.length != 3) {
            System.out.println("");
            System.out.println("Usage:");
            System.out.println("");
            System.out.println("   JDBCPopulate system collectionName tableName");
            System.out.println("");
            System.out.println("");
            System.out.println("For example:");
            System.out.println("");
            System.out.println("");
            System.out.println("   JDBCPopulate MySystem MyLibrary MyTable");
            System.out.println("");
            return;
        }

        String system           = parameters[0];
        String collectionName   = parameters[1];
        String tableName        = parameters[2];

        Connection connection   = null;

        try {

			
            DriverManager.registerDriver(new com.ibm.as400.access.AS400JDBCDriver());  Note 1 

			
            connection = DriverManager.getConnection ("jdbc:as400://"
                + system + "/" + collectionName);  Note 2 

            try {
                Statement dropTable = connection.createStatement ();
                dropTable.executeUpdate ("DROP TABLE " + tableName);  Note 3 
            }
            catch (SQLException e) {
            }

            
            Statement createTable = connection.createStatement ();
            createTable.executeUpdate ("CREATE TABLE " + tableName
                + " (I INTEGER, WORD VARCHAR(20), SQUARE INTEGER, "
                + " SQUAREROOT DOUBLE)");  Note 4 

            
            PreparedStatement insert = connection.prepareStatement ("INSERT INTO "
                + tableName + " (I, WORD, SQUARE, SQUAREROOT) "
                + " VALUES (?, ?, ?, ?)");  Note 5 

            
            for (int i = 1; i <= words.length; ++i) {
                insert.setInt (1, i); 
                insert.setString (2, words[i-1]); 
                insert.setInt (3, i*i); 
                insert.setDouble (4, Math.sqrt(i)); 
                insert.executeUpdate ();  Note 6 
            }

            System.out.println ("Table " + collectionName + "." + tableName
                + " has been populated.");
        }

        catch (Exception e) {
            System.out.println ();
            System.out.println ("ERROR: " + e.getMessage());
        }

        finally {

            try {
                if (connection != null)
                    connection.close ();  Note 7 
            }
            catch (SQLException e) {
                // Ignore.
            }
        }

        System.exit (0);
    }

}

1. This line loads the IBM^® Toolbox for Java™ JDBC driver. A JDBC driver is necessary to mediate between JDBC and the database you are working with.
2. This statement connects to the database. A prompt will appear for the user ID and password. A default schema is provided so that you will not need to qualify the table name in SQL statements.
3. These lines delete the table if it already exists.
4. These lines create the table.
5. This line prepares a statement that will insert rows into the table. Because you will be executing this statement several times, you should use a PreparedStatement and parameter markers.
6. This block of code populates the table for you; every time the loop is executed, it inserts a row into the table.
7. Now that the table has been created and filled in, this statement closes the connection to the database.

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