kotkabeans
Class DB

java.lang.Object
  |
  +--kotkabeans.DB

Direct Known Subclasses:

AddUserToCourse, UserToGroup

public class DB

extends java.lang.Object

provides a connection to the Kotka database to the other beans.

Field Summary

protected java.text.DateFormat	df Field is used to format timestamp output to log-file.
protected java.sql.Connection	myconn Stores used database connection.
protected java.sql.Statement	stmt Used to carry out database operations.
protected boolean	transaction Set to true if transaction has been started.

Constructor Summary

DB()

Method Summary

void	abortTransaction() Flushes transaction-buffer without executing commands.
void	beginTransaction() Starts collecting SQL-commands to buffer, which are executed later as a single block.
void	connect() Requests connection to the Kotka-database.
void	disconnect() Releases used connection.
void	endTransaction() Executes SQL-commands from buffer created by beginTransaction()-method.
java.sql.ResultSet	executeQuery(java.lang.String sqlSentence) Executes SQL-query and establishes connection if needed.
int	executeUpdate(java.lang.String sqlSentence) Executes SQL-update and registeres it to the log file.

Methods inherited from class java.lang.Object

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

Field Detail

myconn

protected java.sql.Connection myconn

Stores used database connection. if null, connect()-method is called when one tries to use database-oriented methods.

See Also:

connect()

stmt

protected java.sql.Statement stmt

Used to carry out database operations. Initialized during connect()-method.

See Also:

connect()

df

protected java.text.DateFormat df

Field is used to format timestamp output to log-file.

transaction

protected boolean transaction

Set to true if transaction has been started. Othervise false

Constructor Detail

DB

public DB()

Method Detail

connect

public void connect()
             throws java.lang.Exception

Requests connection to the Kotka-database. Connections are handled by Poolman. Sets internal variables.

disconnect

public void disconnect()
                throws java.lang.Exception

Releases used connection.

executeQuery

public java.sql.ResultSet executeQuery(java.lang.String sqlSentence)
                                throws java.lang.Exception

Executes SQL-query and establishes connection if needed.

Parameters:

sqlSentence - SQL-query to execute

Returns:

ResultSet containing matching lines

executeUpdate

public int executeUpdate(java.lang.String sqlSentence)
                  throws java.lang.Exception

Executes SQL-update and registeres it to the log file. New connection is requested if no one exists allready.

Parameters:

sqlSentence - SQL-update to execute

beginTransaction

public void beginTransaction()
                      throws java.lang.Exception

Starts collecting SQL-commands to buffer, which are executed later as a single block. Method does nothing if there is allready an active transaction.

endTransaction

public void endTransaction()
                    throws java.lang.Exception

Executes SQL-commands from buffer created by beginTransaction()-method. If there is no active transaction, method does nothing.

See Also:

beginTransaction()

abortTransaction

public void abortTransaction()
                      throws java.lang.Exception

Flushes transaction-buffer without executing commands. If there is no active transaction, method does nothing.

See Also:

beginTransaction()