edu.udo.cs.yale.tools.jdbc
Class DatabaseHandler

java.lang.Object
  edu.udo.cs.yale.tools.jdbc.DatabaseHandler

public class DatabaseHandler
extends java.lang.Object

This class hides the database. Using connect(String,String,boolean), you can extablish a connection to the database. Once connected, queries and updates are possible.

Version:

$Id: DatabaseHandler.java,v 1.6 2006/09/29 10:59:41 ingomierswa Exp $

Author:

Timm Euler, Ingo Mierswa, Simon Fischer

Field Summary

private java.lang.String	databaseURL
private java.sql.Connection	myCon

Constructor Summary

DatabaseHandler(java.lang.String databaseURL)
Constructor of the database handler.

Method Summary

void	addColumn(Attribute attribute, java.lang.String tableName) Adds a column for the given attribute to the table with name tableName.
void	commit() Makes all changes to the database permanent.
void	connect(java.lang.String username, java.lang.String passwd, boolean autoCommit) Establishes a connection to the database.
int	countRecords(java.sql.ResultSet rs) Counts the number of records in the given result set.
static java.util.List<Attribute>	createAttributes(java.sql.ResultSet rs) Creates a list of attributes reflecting the result set's column meta data.
void	disconnect() Closes the connection to the database.
private java.util.List<java.lang.String>	getAllColumnNames(java.lang.String tableName)
java.util.Map<java.lang.String,java.util.List<java.lang.String>>	getAllTableMetaData()
static java.lang.String	getDatabaseName(Attribute attribute)
static int	getYaleTypeIndex(int sqlType) Returns for the given SQL-type the name of the corresponding Yale-Type from edu.udo.cs.yale.tools.Ontology.
java.sql.ResultSet	query(java.lang.String sqlQuery) Executes the given SQL-Query.
void	removeColumn(Attribute attribute, java.lang.String tableName) Removes the column of the given attribute from the table with name tableName.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

databaseURL

private java.lang.String databaseURL

myCon

private java.sql.Connection myCon

Constructor Detail

DatabaseHandler

public DatabaseHandler(java.lang.String databaseURL)

Constructor of the database handler. This constructor expects the URL definition of the database which is needed by the System DriverManager to create an appropriate driver.

Method Detail

connect

public void connect(java.lang.String username,
                    java.lang.String passwd,
                    boolean autoCommit)
             throws java.sql.SQLException

Establishes a connection to the database. Afterwards, queries and updates can be executed using the methods this class provides.

Parameters:

username - Name with which to log in to the database.

passwd - Password with which to log in to the database.

autoCommit - If TRUE, all changes to the database will be committed automatically. If FALSE, the commit()-Method has to be called to make changes permanent.

Throws:

java.sql.SQLException

disconnect

public void disconnect()
                throws java.sql.SQLException

Closes the connection to the database.

Throws:

java.sql.SQLException

query

public java.sql.ResultSet query(java.lang.String sqlQuery)
                         throws java.sql.SQLException

Executes the given SQL-Query. Only SQL-statements starting with "SELECT" (disregarding case) will be accepted. Any errors will result in an SQL-Exception being thrown.

Parameters:

sqlQuery - An SQL-String.

Returns:

A ResultSet-Object with the results of the query. The ResultSet is scrollable, but not not updatable. It will not show changes to the database made by others after this ResultSet was obtained.

Throws:

java.sql.SQLException

addColumn

public void addColumn(Attribute attribute,
                      java.lang.String tableName)
               throws java.sql.SQLException

Adds a column for the given attribute to the table with name tableName.

Throws:

java.sql.SQLException

removeColumn

public void removeColumn(Attribute attribute,
                         java.lang.String tableName)
                  throws java.sql.SQLException

Removes the column of the given attribute from the table with name tableName.

Throws:

java.sql.SQLException

countRecords

public int countRecords(java.sql.ResultSet rs)
                 throws java.sql.SQLException

Counts the number of records in the given result set.

Parameters:

rs - The ResultSet.

Throws:

java.sql.SQLException

commit

public void commit()
            throws java.sql.SQLException

Makes all changes to the database permanent.

Throws:

java.sql.SQLException

getYaleTypeIndex

public static int getYaleTypeIndex(int sqlType)

Returns for the given SQL-type the name of the corresponding Yale-Type from edu.udo.cs.yale.tools.Ontology.

createAttributes

public static java.util.List<Attribute> createAttributes(java.sql.ResultSet rs)
                                                  throws java.sql.SQLException

Creates a list of attributes reflecting the result set's column meta data.

Throws:

java.sql.SQLException

getDatabaseName

public static java.lang.String getDatabaseName(Attribute attribute)

getAllTableMetaData

public java.util.Map<java.lang.String,java.util.List<java.lang.String>> getAllTableMetaData()
                                                                                     throws java.sql.SQLException

Throws:

java.sql.SQLException

getAllColumnNames

private java.util.List<java.lang.String> getAllColumnNames(java.lang.String tableName)
                                                    throws java.sql.SQLException

Throws:

java.sql.SQLException