javatools.database

Class OracleDatabase

java.lang.Object

javatools.database.Database

javatools.database.OracleDatabase

public class OracleDatabase
extends Database

This class is part of the Java Tools (see http://mpii.de/yago-naga/javatools). It is licensed under the Creative Commons Attribution License (see http://creativecommons.org/licenses/by/3.0) by the YAGO-NAGA team (see http://mpii.de/yago-naga). The class OracleDatabase implements the Database-interface for an Oracle SQL data base. Make sure that the file "classes12.jar" of the Oracle distribution is in the classpath. When using Eclipse, add the file via Project ->Properties ->JavaBuildPath ->Libraries ->ExternalJARFile.
Example:

     Database d=new OracleDatabase("user","password");
     d.queryColumn("SELECT foodname FROM food WHERE origin=\"Italy\"")
     -> [ "Pizza Romana", "Spaghetti alla Bolognese", "Saltimbocca"]
     Database.describe(d.query("SELECT * FROM food WHERE origin=\"Italy\"")
     -> foodname |origin  |calories |
        ------------------------------
        Pizza Rom|Italy   |10000    |
        Spaghetti|Italy   |8000     |
        Saltimboc|Italy   |8000     |

This class also provides SQL datatypes (extensions of SQLType.java) that behave according to the conventions of Oracle. For example, the ANSI SQL datatype BOOLEAN is mapped to NUMBER(1). Furthermore, VARCHAR string literals print inner quotes as doublequotes.

Oracle (and only Oracle!) often complains "ORA-01000: maximum open cursors exceeded". This does not necessarily mean that the maximum number of open cursors is exceeded. It can also mean that your SQL statement has an invalid character. Check your SQL statements carefully. If the statements are OK, try the following:

• Avoid query() whenever possible and use executeQuery(), queryValue and query/ResultIterator instead, because these close the open resources automatically.
• If you use query(), be sure to call Database.close(ResultSet) afterwards.
• Reset the connection from time to time by calling resetConnection(). (This is an Oracle-specific trick).
• Increase the number of cursors in Oracle by saying dabatase.executeUpdate("ALTER SYSTEM SET open_cursors=1000000 scope=both")

The simplest solution, though, is to use another database. Postgres and MySQL can be downloaded for free, PostgresDatabase.java and MySQLDatabase.java provide the respective Java-adapters.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	OracleDatabase.Bigint
static class	OracleDatabase.Bool
static class	OracleDatabase.Varchar

Nested classes/interfaces inherited from class javatools.database.Database

Database.CommitTransactionSQLException, Database.ConnectionBrokenSQLException, Database.InitTransactionSQLException, Database.Inserter, Database.RollbackTransactionSQLException, Database.StartAutoCommitSQLException, Database.TransactionSQLException

Field Summary

Fields

Modifier and Type	Field and Description
static OracleDatabase.Bigint	bigint
static OracleDatabase.Bool	bool
protected java.lang.String	connectionString Holds the String by which the connection can be reset
static OracleDatabase.Varchar	varchar

Fields inherited from class javatools.database.Database

connection, description, driver, fetchsize, inserters, java2SQL, MINCOLUMNWIDTH, resultSetConcurrency, resultSetType, SCREENWIDTH, type2SQL

Constructor Summary

Constructors

Constructor and Description
OracleDatabase() Constructs a non-functional OracleDatabase for use of getSQLType
OracleDatabase(java.lang.String user, java.lang.String password) Constructs a new OracleDatabase from a user and a password on the localhost
OracleDatabase(java.lang.String user, java.lang.String password, java.lang.String host) Constructs a new OracleDatabase from a user, a password and a host
OracleDatabase(java.lang.String user, java.lang.String password, java.lang.String host, java.lang.String port) Constructs a new OracleDatabase from a user, a password and a host
OracleDatabase(java.lang.String user, java.lang.String password, java.lang.String host, java.lang.String port, java.lang.String inst) Constructs a new OracleDatabase from a user, a password and a host

Method Summary

Modifier and Type	Method and Description
void	connect() connects to the database specified
boolean	connected() Checks whether the connection to the database is still alive
boolean	jarAvailable() TRUE if the required JAR is there
java.lang.String	limit(java.lang.String sql, int n) Makes an SQL query limited to n results
static void	main(java.lang.String[] args)
protected java.lang.String	prepareQuery(java.lang.String sql) Prepares the query internally for a call (deletes trailing semicolon)
void	resetConnection() Deprecated. replaced by Database.reconnect()

Methods inherited from class javatools.database.Database

appendFixedLen, attemptReconnect, autoincrementColumn, cast, close, close, close, close, commitTransaction, createIndex, createIndexCommand, createIndices, createPrimaryKey, createTable, createView, describe, describe, dumpCSV, dumpQueryAsCSV, endTransaction, endTransaction, executeQuery, executeUpdate, executeUpdateQuery, exists, existsTable, finalize, flush, format, formatNullToNull, getConnection, getFetchsize, getResultSetConcurrency, getResultSetType, getSQLStmntIFNULL, getSQLType, getSQLType, getSQLType, getValidityCheckTimeout, indexName, isAutoReconnectingOnSelect, isAutoReconnectingOnUpdate, loadCSV, lockTableReadAccess, lockTableWriteAccess, makeCSV, makeCSVForQuery, newInserter, newInserter, newInserter, offset, query, query, query, query, queryValue, reconnect, releaseLocksAndEndTransaction, resetTransaction, runInterface, setAutoReconnectOnSelect, setAutoReconnectOnUpdate, setFetchsize, setResultSetConcurrency, setResultSetType, setValidityCheckTimeout, startTransaction, toString

Methods inherited from class java.lang.Object

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

Field Detail

connectionString

protected java.lang.String connectionString

Holds the String by which the connection can be reset

varchar

public static OracleDatabase.Varchar varchar

bool

public static OracleDatabase.Bool bool

bigint

public static OracleDatabase.Bigint bigint

Constructor Detail

OracleDatabase

public OracleDatabase()

Constructs a non-functional OracleDatabase for use of getSQLType

OracleDatabase

public OracleDatabase(java.lang.String user,
                      java.lang.String password,
                      java.lang.String host)
               throws java.lang.InstantiationException,
                      java.lang.IllegalAccessException,
                      java.lang.ClassNotFoundException,
                      java.sql.SQLException

Constructs a new OracleDatabase from a user, a password and a host

Throws:

java.lang.InstantiationException

java.lang.IllegalAccessException

java.lang.ClassNotFoundException

java.sql.SQLException

OracleDatabase

public OracleDatabase(java.lang.String user,
                      java.lang.String password,
                      java.lang.String host,
                      java.lang.String port)
               throws java.lang.InstantiationException,
                      java.lang.IllegalAccessException,
                      java.lang.ClassNotFoundException,
                      java.sql.SQLException

Constructs a new OracleDatabase from a user, a password and a host

Throws:

java.lang.InstantiationException

java.lang.IllegalAccessException

java.lang.ClassNotFoundException

java.sql.SQLException

OracleDatabase

public OracleDatabase(java.lang.String user,
                      java.lang.String password,
                      java.lang.String host,
                      java.lang.String port,
                      java.lang.String inst)
               throws java.lang.InstantiationException,
                      java.lang.IllegalAccessException,
                      java.lang.ClassNotFoundException,
                      java.sql.SQLException

Constructs a new OracleDatabase from a user, a password and a host

Throws:

java.lang.ClassNotFoundException

java.lang.IllegalAccessException

java.lang.InstantiationException

java.sql.SQLException

OracleDatabase

public OracleDatabase(java.lang.String user,
                      java.lang.String password)
               throws java.lang.Exception

Constructs a new OracleDatabase from a user and a password on the localhost

Throws:

java.lang.Exception

Method Detail

prepareQuery

protected java.lang.String prepareQuery(java.lang.String sql)

Prepares the query internally for a call (deletes trailing semicolon)

Overrides:

prepareQuery in class Database

resetConnection

@Deprecated
public void resetConnection()
                                 throws java.sql.SQLException

Deprecated. replaced by Database.reconnect()

Resets the connection.

Throws:

java.sql.SQLException

connect

public void connect()
             throws java.sql.SQLException

connects to the database specified

Specified by:

connect in class Database

Throws:

java.sql.SQLException

limit

public java.lang.String limit(java.lang.String sql,
                              int n)

Makes an SQL query limited to n results

Overrides:

limit in class Database

jarAvailable

public boolean jarAvailable()

Description copied from class: Database

TRUE if the required JAR is there

Overrides:

jarAvailable in class Database

connected

public boolean connected()

Checks whether the connection to the database is still alive

Overrides:

connected in class Database

main

public static void main(java.lang.String[] args)