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## weka.experiment
Class DatabaseUtils

    java.lang.Object
      weka.experiment.DatabaseUtils

All Implemented Interfaces:
  java.io.Serializable

Direct Known Subclasses:
  DatabaseConnection, DatabaseResultListener, InstanceQuery

    public class DatabaseUtils

extends java.lang.Object
implements java.io.Serializable

DatabaseUtils provides utility functions for accessing the experiment database. The jdbc driver and database to be used default to "jdbc.idbDriver" and "jdbc:idb=experiments.prp". These may be changed by creating a java properties file called DatabaseUtils.props in user.home or the current directory. eg:

``

     jdbcDriver=jdbc.idbDriver
     jdbcURL=jdbc:idb=experiments.prp

Version:
  $Revision: 1.18.2.7 $
Author:
  Len Trigg (trigg@cs.waikato.ac.nz)
See Also:
  Serialized Form

Field Summary
`static int` | `BOOL` Type mapping for BOOL used for reading experiment results
`static int` | `BYTE` Type mapping for BYTE used for reading experiment results
`static int` | `DATE` Type mapping for DATE used for reading experiment results
`static int` | `DOUBLE` Type mapping for DOUBLE used for reading experiment results
`static java.lang.String` | `EXP_INDEX_TABLE` The name of the table containing the index to experiments
`static java.lang.String` | `EXP_RESULT_COL` The name of the column containing the results table name
`static java.lang.String` | `EXP_RESULT_PREFIX` The prefix for result table names
`static java.lang.String` | `EXP_SETUP_COL` The name of the column containing the experiment setup (parameters)
`static java.lang.String` | `EXP_TYPE_COL` The name of the column containing the experiment type (ResultProducer)
`static int` | `FLOAT` Type mapping for FLOAT used for reading experiment results
`static int` | `INTEGER` Type mapping for INTEGER used for reading experiment results
`static int` | `LONG` Type mapping for LONG used for reading experiment results
`static java.lang.String` | `PROPERTY_FILE` The name of the properties file
`static int` | `SHORT` Type mapping for SHORT used for reading experiment results
`static int` | `STRING` Type mapping for STRING used for reading experiment results

Constructor Summary
`DatabaseUtils()` Reads properties and sets up the database drivers

Method Summary
`static java.lang.String` | `arrayToString(java.lang.Object[] array)` Converts an array of objects to a string by inserting a space between each element.
`void` | `connectToDatabase()` Opens a connection to the database
`void` | `createExperimentIndex()` Attempts to create the experiment index table
`java.lang.String` | `createExperimentIndexEntry(ResultProducer rp)` Attempts to insert a results entry for the table into the experiment index.
`java.lang.String` | `createResultsTable(ResultProducer rp, java.lang.String tableName)` Creates a results table for the supplied result producer.
`java.lang.String` | `databaseURLTipText()` Returns the tip text for this property
`java.lang.String` | `debugTipText()` Returns the tip text for this property
`void` | `disconnectFromDatabase()` Closes the connection to the database.
`boolean` | `execute(java.lang.String query)` Executes a SQL query.
`boolean` | `experimentIndexExists()` Returns true if the experiment index exists.
`java.lang.String` | `getDatabaseURL()` Get the value of DatabaseURL.
`boolean` | `getDebug()` Gets whether there should be printed some debugging output to stderr or not
`java.lang.String` | `getPassword()` Get the database password
`java.lang.Object[]` | `getResultFromTable(java.lang.String tableName, ResultProducer rp, java.lang.Object[] key)` Executes a database query to extract a result for the supplied key from the database.
`java.sql.ResultSet` | `getResultSet()` Gets the results generated by a previous query.
`java.lang.String` | `getResultsTableName(ResultProducer rp)` Gets the name of the experiment table that stores results from a particular ResultProducer.
`java.lang.String` | `getUsername()` Get the database username
`boolean` | `isConnected()` Returns true if a database connection is active.
`java.lang.String` | `passwordTipText()` Returns the tip text for this property
`static java.lang.String` | `processKeyString(java.lang.String s)` processes the string in such a way that it can be stored in the database, i.e., it changes backslashes into slashes and doubles single quotes.
`void` | `putResultInTable(java.lang.String tableName, ResultProducer rp, java.lang.Object[] key, java.lang.Object[] result)` Executes a database query to insert a result for the supplied key into the database.
`void` | `setDatabaseURL(java.lang.String newDatabaseURL)` Set the value of DatabaseURL.
`void` | `setDebug(boolean d)` Sets whether there should be printed some debugging output to stderr or not
`void` | `setPassword(java.lang.String password)` Set the database password
`void` | `setUsername(java.lang.String username)` Set the database username
`boolean` | `tableExists(java.lang.String tableName)` Checks that a given table exists.
`int` | `translateDBColumnType(java.lang.String type)` translates the column data type string to an integer value that indicates which data type / get()-Method to use in order to retrieve values from the database (see DatabaseUtils.Properties, InstanceQuery()).
`static java.lang.String` | `typeName(int type)` Returns the name associated with a SQL type.
`java.lang.String` | `usernameTipText()` Returns the tip text for this property

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### EXP_INDEX_TABLE

    public static final java.lang.String EXP_INDEX_TABLE

  The name of the table containing the index to experiments

  See Also:
    Constant Field Values

### EXP_TYPE_COL

    public static final java.lang.String EXP_TYPE_COL

  The name of the column containing the experiment type (ResultProducer)

  See Also:
    Constant Field Values

### EXP_SETUP_COL

    public static final java.lang.String EXP_SETUP_COL

  The name of the column containing the experiment setup (parameters)

  See Also:
    Constant Field Values

### EXP_RESULT_COL

    public static final java.lang.String EXP_RESULT_COL

  The name of the column containing the results table name

  See Also:
    Constant Field Values

### EXP_RESULT_PREFIX

    public static final java.lang.String EXP_RESULT_PREFIX

  The prefix for result table names

  See Also:
    Constant Field Values

### PROPERTY_FILE

    public static final java.lang.String PROPERTY_FILE

  The name of the properties file

  See Also:
    Constant Field Values

### STRING

    public static final int STRING

  Type mapping for STRING used for reading experiment results

  See Also:
    Constant Field Values

### BOOL

    public static final int BOOL

  Type mapping for BOOL used for reading experiment results

  See Also:
    Constant Field Values

### DOUBLE

    public static final int DOUBLE

  Type mapping for DOUBLE used for reading experiment results

  See Also:
    Constant Field Values

### BYTE

    public static final int BYTE

  Type mapping for BYTE used for reading experiment results

  See Also:
    Constant Field Values

### SHORT

    public static final int SHORT

  Type mapping for SHORT used for reading experiment results

  See Also:
    Constant Field Values

### INTEGER

    public static final int INTEGER

  Type mapping for INTEGER used for reading experiment results

  See Also:
    Constant Field Values

### LONG

    public static final int LONG

  Type mapping for LONG used for reading experiment results

  See Also:
    Constant Field Values

### FLOAT

    public static final int FLOAT

  Type mapping for FLOAT used for reading experiment results

  See Also:
    Constant Field Values

### DATE

    public static final int DATE

  Type mapping for DATE used for reading experiment results

  See Also:
    Constant Field Values

Constructor Detail

### DatabaseUtils

    public DatabaseUtils()
                  throws java.lang.Exception

  Reads properties and sets up the database drivers

  Throws:
    `java.lang.Exception` - if an error occurs

Method Detail

### translateDBColumnType

    public int translateDBColumnType(java.lang.String type)

  translates the column data type string to an integer value that indicates which data type / get()-Method to use in order to retrieve values from the database (see DatabaseUtils.Properties, InstanceQuery()). Blanks in the type are replaced with underscores "_", since Java property names can't contain blanks.

  Parameters:
    `type` - the column type as retrieved with java.sql.MetaData.getColumnTypeName(int)
  Returns:
    an integer value that indicates which data type / get()-Method to use in order to retrieve values from the

### arrayToString

    public static java.lang.String arrayToString(java.lang.Object[] array)

  Converts an array of objects to a string by inserting a space between each element. Null elements are printed as ?

  Parameters:
    `array` - the array of objects
  Returns:
    a value of type 'String'

### typeName

    public static java.lang.String typeName(int type)

  Returns the name associated with a SQL type.

  Parameters:
    `type` - the SQL type
  Returns:
    the name of the type

### databaseURLTipText

    public java.lang.String databaseURLTipText()

  Returns the tip text for this property

  Returns:
    tip text for this property suitable for displaying in the explorer/experimenter gui

### getDatabaseURL

    public java.lang.String getDatabaseURL()

  Get the value of DatabaseURL.

  Returns:
    Value of DatabaseURL.

### setDatabaseURL

    public void setDatabaseURL(java.lang.String newDatabaseURL)

  Set the value of DatabaseURL.

  Parameters:
    `newDatabaseURL` - Value to assign to DatabaseURL.

### debugTipText

    public java.lang.String debugTipText()

  Returns the tip text for this property

  Returns:
    tip text for this property suitable for displaying in the explorer/experimenter gui

### setDebug

    public void setDebug(boolean d)

  Sets whether there should be printed some debugging output to stderr or not

  Parameters:
    `d` - true if output should be printed

### getDebug

    public boolean getDebug()

  Gets whether there should be printed some debugging output to stderr or not

  Returns:
    true if output should be printed

### usernameTipText

    public java.lang.String usernameTipText()

  Returns the tip text for this property

  Returns:
    tip text for this property suitable for displaying in the explorer/experimenter gui

### setUsername

    public void setUsername(java.lang.String username)

  Set the database username

  Parameters:
    `username` - Username for Database.

### getUsername

    public java.lang.String getUsername()

  Get the database username

  Returns:
    Database username

### passwordTipText

    public java.lang.String passwordTipText()

  Returns the tip text for this property

  Returns:
    tip text for this property suitable for displaying in the explorer/experimenter gui

### setPassword

    public void setPassword(java.lang.String password)

  Set the database password

  Parameters:
    `password` - Password for Database.

### getPassword

    public java.lang.String getPassword()

  Get the database password

  Returns:
    Password for Database.

### connectToDatabase

    public void connectToDatabase()
                           throws java.lang.Exception

  Opens a connection to the database

  Throws:
    `java.lang.Exception` - if an error occurs

### disconnectFromDatabase

    public void disconnectFromDatabase()
                                throws java.lang.Exception

  Closes the connection to the database.

  Throws:
    `java.lang.Exception` - if an error occurs

### isConnected

    public boolean isConnected()

  Returns true if a database connection is active.

  Returns:
    a value of type 'boolean'

### execute

    public boolean execute(java.lang.String query)
                    throws java.sql.SQLException

  Executes a SQL query.

  Parameters:
    `query` - the SQL query
  Returns:
    true if the query generated results
  Throws:
    `java.sql.SQLException` - if an error occurs

### getResultSet

    public java.sql.ResultSet getResultSet()
                                    throws java.sql.SQLException

  Gets the results generated by a previous query.

  Returns:
    the result set.
  Throws:
    `java.sql.SQLException` - if an error occurs

### tableExists

    public boolean tableExists(java.lang.String tableName)
                        throws java.lang.Exception

  Checks that a given table exists.

  Parameters:
    `tableName` - the name of the table to look for.
  Returns:
    true if the table exists.
  Throws:
    `java.lang.Exception` - if an error occurs.

### processKeyString

    public static java.lang.String processKeyString(java.lang.String s)

  processes the string in such a way that it can be stored in the database, i.e., it changes backslashes into slashes and doubles single quotes.

  Parameters:
    `s` - the string to work on
  Returns:
    the processed string

### getResultFromTable

    public java.lang.Object[] getResultFromTable(java.lang.String tableName,
                                                 ResultProducer rp,
                                                 java.lang.Object[] key)
                                          throws java.lang.Exception

  Executes a database query to extract a result for the supplied key from the database.

  Parameters:
    `tableName` - the name of the table where the result is stored
    `rp` - the ResultProducer who will generate the result if required
    `key` - the key for the result
  Returns:
    true if the result with that key is in the database already
  Throws:
    `java.lang.Exception` - if an error occurs

### putResultInTable

    public void putResultInTable(java.lang.String tableName,
                                 ResultProducer rp,
                                 java.lang.Object[] key,
                                 java.lang.Object[] result)
                          throws java.lang.Exception

  Executes a database query to insert a result for the supplied key into the database.

  Parameters:
    `tableName` - the name of the table where the result is stored
    `rp` - the ResultProducer who will generate the result if required
    `key` - the key for the result
    `result` - the result to store
  Throws:
    `java.lang.Exception` - if an error occurs

### experimentIndexExists

    public boolean experimentIndexExists()
                                  throws java.lang.Exception

  Returns true if the experiment index exists.

  Returns:
    true if the index exists
  Throws:
    `java.lang.Exception` - if an error occurs

### createExperimentIndex

    public void createExperimentIndex()
                               throws java.lang.Exception

  Attempts to create the experiment index table

  Throws:
    `java.lang.Exception` - if an error occurs.

### createExperimentIndexEntry

    public java.lang.String createExperimentIndexEntry(ResultProducer rp)
                                                throws java.lang.Exception

  Attempts to insert a results entry for the table into the experiment index.

  Parameters:
    `rp` - the ResultProducer generating the results
  Returns:
    the name of the created results table
  Throws:
    `java.lang.Exception` - if an error occurs.

### getResultsTableName

    public java.lang.String getResultsTableName(ResultProducer rp)
                                         throws java.lang.Exception

  Gets the name of the experiment table that stores results from a particular ResultProducer.

  Parameters:
    `rp` - the ResultProducer
  Returns:
    the name of the table where the results for this ResultProducer are stored, or null if there is no table for this ResultProducer.
  Throws:
    `java.lang.Exception` - if an error occurs

### createResultsTable

    public java.lang.String createResultsTable(ResultProducer rp,
                                               java.lang.String tableName)
                                        throws java.lang.Exception

  Creates a results table for the supplied result producer.

  Parameters:
    `rp` - the ResultProducer generating the results
    `tableName` - the name of the resultsTable
  Returns:
    the name of the created results table
  Throws:
    `java.lang.Exception` - if an error occurs.

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