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HSQL Database error  RSS feed

Posts: 5
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Need some help. Using databases for the first time.

I have downloaded the hsql database and they provide a file. When I run this, I get the following exception:

java.lang.ClassNotFoundException: org.hsqldb.jdbc.JDBCDriver

at the line: Class.forName("org.hsqldb.jdbc.JDBCDriver");

Does someone know how to fix this error?

Akshay Jain
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Here is the entire Testdb file:

package org.hsqldb.sample;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;

* Title: Testdb
* Description: simple hello world db example of a
* standalone persistent db application
* every time it runs it adds four more rows to sample_table
* it does a query and prints the results to standard out
* Author: Karl Meissner
public class Testdb {

Connection conn; //our connnection to the db - presist for life of program

// we dont want this garbage collected until we are done
public Testdb(String db_file_name_prefix) throws Exception { // note more general exception

// Load the HSQL Database Engine JDBC driver
// hsqldb.jar should be in the class path or made part of the current jar

// connect to the database. This will load the db files and start the
// database if it is not alread running.
// db_file_name_prefix is used to open or create files that hold the state
// of the db.
// It can contain directory names relative to the
// current working directory
conn = DriverManager.getConnection("jdbc:hsqldb:"
+ db_file_name_prefix, // filenames
"SA", // username
""); // password

public void shutdown() throws SQLException {

Statement st = conn.createStatement();

// db writes out to files and performs clean shuts down
// otherwise there will be an unclean shutdown
// when program ends
conn.close(); // if there are no other open connection

//use for SQL command SELECT
public synchronized void query(String expression) throws SQLException {

Statement st = null;
ResultSet rs = null;

st = conn.createStatement(); // statement objects can be reused with

// repeated calls to execute but we
// choose to make a new one each time
rs = st.executeQuery(expression); // run the query

// do something with the result set.
st.close(); // NOTE!! if you close a statement the associated ResultSet is

// closed too
// so you should copy the contents to some other object.
// the result set is invalidated also if you recycle an Statement
// and try to execute some other query before the result set has been
// completely examined.

//use for SQL commands CREATE, DROP, INSERT and UPDATE
public synchronized void update(String expression) throws SQLException {

Statement st = null;

st = conn.createStatement(); // statements

int i = st.executeUpdate(expression); // run the query

if (i == -1) {
System.out.println("db error : " + expression);

} // void update()

public static void dump(ResultSet rs) throws SQLException {

// the order of the rows in a cursor
// are implementation dependent unless you use the SQL ORDER statement
ResultSetMetaData meta = rs.getMetaData();
int colmax = meta.getColumnCount();
int i;
Object o = null;

// the result set is a cursor into the data. You can only
// point to one row at a time
// assume we are pointing to BEFORE the first row
// points to next row and returns true
// or false if there is no next row, which breaks the loop
for (;; ) {
for (i = 0; i < colmax; ++i) {
o = rs.getObject(i + 1); // Is SQL the first column is indexed

// with 1 not 0
System.out.print(o.toString() + " ");

System.out.println(" ");
} //void dump( ResultSet rs )

public static void main(String[] args) {

Testdb db = null;

try {
db = new Testdb("db_file");
} catch (Exception ex1) {
ex1.printStackTrace(); // could not start db

return; // bye bye

try {

//make an empty table
// by declaring the id column IDENTITY, the db will automatically
// generate unique values for new rows- useful for row keys
"CREATE TABLE sample_table ( id INTEGER IDENTITY, str_col VARCHAR(256), num_col INTEGER)");
} catch (SQLException ex2) {

//ex2.printStackTrace(); // second time we run program
// should throw execption since table
// already there
// this will have no effect on the db

try {

// add some rows - will create duplicates if run more then once
// the id column is automatically generated
"INSERT INTO sample_table(str_col,num_col) VALUES('Ford', 100)");
"INSERT INTO sample_table(str_col,num_col) VALUES('Toyota', 200)");
"INSERT INTO sample_table(str_col,num_col) VALUES('Honda', 300)");
"INSERT INTO sample_table(str_col,num_col) VALUES('GM', 400)");

// do a query
db.query("SELECT * FROM sample_table WHERE num_col < 250");

// at end of program
} catch (SQLException ex3) {
} // main()
} // class Testdb

Here is the exception/stack trace:

java.lang.ClassNotFoundException: org.hsqldb.jdbc.JDBCDriver
at Method)
at java.lang.ClassLoader.loadClass(
at sun.misc.Launcher$AppClassLoader.loadClass(
at java.lang.ClassLoader.loadClass(
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(
at org.hsqldb.sample.Testdb.<init>(
at org.hsqldb.sample.Testdb.main(

Saloon Keeper
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You need to add the HSQLDB jar file to the classpath whenever you intend to use any of its classes.
Ranch Hand
Posts: 754
Eclipse IDE Java
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This post shows how to join JUnit with HSQLDB, step by step: JUnit with HSQLDB, JPA and Hibernate.

I show the steps to use the HSQLDB with an application.

I hope it helps you.
It is sorta covered in the JavaRanch Style Guide.
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