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### Mckoi SQL Database as an embedded application Index

> 1. Using an embedded Mckoi Database from within your JavaTM application
> 2. Using the JDBC Query Tool on a local database

1. Using an embedded Mckoi Database from within your JavaTM application

> The following program code demonstrates how to embed a local Mckoi database within your JavaTM application;

>     import java.sql.*;

>     public class EmbeddedDatabaseDemo {

>       public static void main(String[] args) {

>         // Register the Mckoi JDBC Driver
>         try {
>           Class.forName("com.mckoi.JDBCDriver").newInstance();
>         }
>         catch (Exception e) {
>           System.out.println(
>             "Unable to register the JDBC Driver.\n" +
>             "Make sure the JDBC driver is in the\n" +
>             "classpath.\n" +
>           System.exit(1);
>         }

>         // This URL specifies we are connecting with a local database
>         // within the file system.  './db.conf' is the path of the
>         // configuration file of the database to embed.
>         String url = "jdbc:mckoi:local://./db.conf";

>         // The username / password to connect under.
>         String username = "admin_user";
>         String password = "aupass00";

>         // Make a connection with the local database.
>         Connection connection;
>         try {
>           connection = DriverManager.getConnection(url, username, password);
>         }
>         catch (SQLException e) {
>           System.out.println(
>             "Unable to make a connection to the database.\n" +
>             "The reason: " + e.getMessage());
>           System.exit(1);
>           return;
>         }

>         try {

>           // .... Use 'connection' to talk to database ....

>           // Close the connection when finished,
>           connection.close();

>         }
>         catch (SQLException e) {
>           System.out.println(
>             "An error occured\n" +
>             "The SQLException message is: " + e.getMessage());
>           return;
>         }

>       }

>     }

> The `java.sql.Connection` object is used to communicate with the local database.

> It's important to note here that you can only have one Java virtual machine connected to a local database at the same time. If more than one VM is connected to the same local database then the behaviour is undefined and a likely result will be database corruption. If you wish for there to be more than one connection to the same database, use Mckoi SQL Database as a multi-threaded multi-user server (see section 'Mckoi SQL Database as a multi-user server').

> There are working demonstrations of creating / populating and querying a database in the `/demo` directory of the installation.

2. Using the JDBC Query Tool on a local database

> JDBCQueryTool is a simple utility program developed for Mckoi SQL Database. It can connect to a Mckoi database, run queries and display the results graphically. It uses JavaTM Swing/JFC for the user interface. JDBC Query Tool is an interactive tool that is useful for testing queries, examining and setting up a database.

> To use the JDBC Query Tool on a local database, use the following command;

>     java -cp mckoidb.jar com.mckoi.tools.JDBCQueryTool \
>            -url "jdbc:mckoi:local://./db.conf" \
>            -u "admin_user" -p "aupass00"

> This is assuming the configuration file is at path `./db.conf` in the file system, and the username / password is set the same as from the 'Getting Started' section.

> If all was successful, you'll get a window that looks like this;

> Lets create a new table in the database. Enter the following SQL query and click the Run Query button;

>     CREATE TABLE Order (
>         id       INTEGER    NOT NULL UNIQUE,
>         number   STRING(20),
>         part     STRING(20),
>         price    NUMERIC,
>         quantity NUMERIC
>     )

> The screen should end up looking like this;

> Now populate the Order table with some entries. Enter the following SQL Query (or put in some different values if you like) and click on the Run Query button.

>     INSERT INTO Order
>         ( id, number, part, price, quantity )
>       VALUES
>         ( 0, 'OR1', 'PA01', 25.95, 1 )

> The screen should look like this;

> Enter as many additional records into the Order table as you like.

> Now on to a couple of queries on the data in the table. To look at all the records in the Order table, enter the following;

>     SELECT * FROM Order

> You'll get a screen similar to the following (depending on how many order entries you entered);

> Or a more complex query that calculates the total quantity of parts in all orders, the total value of all orders, and the average value of each order...

Last Updated: Mon Nov 18 14:36:45 PST 2002 Mckoi SQL Database Copyright © 2000, 2001, 2002 Diehl and Associates, Inc. All rights reserved.