sample.java

有关JDBC的使用一些编程实例,有关与数据库连接的代码

/**
 * sample - a sample MsqlJava client.
 *
 * @author Brian Jepson
 * @author Copyright 1996, John Wiley and Sons
 *
 * Copyright 1996 John Wiley & Sons, Inc. All Rights Reserved. Reproduction
 * or translation of this work beyond that permitted in Section 117 of the 1976
 * United States Copyright Act without the express written permission of the
 * copyright owner is unlawful. Requests for further information should be 
 * addressed to Permissions Department, John Wiley & Sons, Inc. The 
 * purchaser may make back-up copies for his/her own use only and not for 
 * distribution or resale. The Publisher assumes no responsibility for errors, 
 * omissions, or damages, caused by the use of this  software or from the use
 * of the information contained herein.
 *
 */
import msql.*;

public class sample {

  /**
   * main() - the main method
   *
   * @param argv[0] name of mSQL host (default == localhost)
   *
   */
  public static void main(String argv[]) {

    // instantiate an Msql object...

    Msql msql = new Msql();

    // a hostname can be specified on the command line

    String host;
    if (argv.length > 0) {

      host = argv[0];

    } else {

      // if no hostname was specified, use localhost

      host = "localhost";
    }

    try {

      // make a connection to the specified host,
      // and select the sample database
      
      msql.Connect(host);
      msql.SelectDB("sample");

      // if the "sample_table" already exists, drop it
      // we can determine if the table exists by iterating
      // over the output of ListTables()
      
      String[] tables = msql.ListTables();

      if (tables != null) {

        for (int i = 0; i < tables.length; i++) {
  	  if (tables[i].equals("sample_table")) {
	    msql.Query("drop table sample_table");
	  }
        }

      }

      // create the "sample_table" table

      msql.Query("create table sample_table (name char(15))");

      // insert a few values into it

      msql.Query("insert into sample_table (name) values ('Brian')");
      msql.Query("insert into sample_table (name) values ('Christopher')");
      msql.Query("insert into sample_table (name) values ('David')");
      msql.Query("insert into sample_table (name) values ('Michael')");
      msql.Query("insert into sample_table (name) values ('Nathan')");
      msql.Query("insert into sample_table (name) values ('Ron')");

      // retrieve all of the rows from it

      MsqlResult result = msql.Query("select name from sample_table");

      // fetch each row from the results, and print out
      // the first column. FetchRow returns an array of
      // strings, which positionally correspond to the
      // columns in the result set.

      String row[];
      while(( row = result.FetchRow()) != null) {
	System.out.println("[" + row[0] + "]");
      }

    }

    // print a stack trace if we catch an exception

    catch(MsqlException e ) {
      e.printStackTrace();      
    }

  }
    
}