DatabaseLoader

java.lang.Object
- weka.core.converters.AbstractLoader
- - weka.core.converters.DatabaseLoader

All Implemented Interfaces:

java.io.Serializable, BatchConverter, DatabaseConverter, IncrementalConverter, Loader, EnvironmentHandler, OptionHandler, RevisionHandler
```
public class DatabaseLoader
extends AbstractLoader
implements BatchConverter, IncrementalConverter, DatabaseConverter, OptionHandler, EnvironmentHandler
```
Reads Instances from a Database. Can read a database in batch or incremental mode.
In inremental mode MySQL and HSQLDB are supported.
For all other DBMS set a pseudoincremental mode is used:
In pseudo incremental mode the instances are read into main memory all at once and then incrementally provided to the user.
For incremental loading the rows in the database table have to be ordered uniquely.
The reason for this is that every time only a single row is fetched by extending the user query by a LIMIT clause.
If this extension is impossible instances will be loaded pseudoincrementally. To ensure that every row is fetched exaclty once, they have to ordered.
Therefore a (primary) key is necessary.This approach is chosen, instead of using JDBC driver facilities, because the latter one differ betweeen different drivers.
If you use the DatabaseSaver and save instances by generating automatically a primary key (its name is defined in DtabaseUtils), this primary key will be used for ordering but will not be part of the output. The user defined SQL query to extract the instances should not contain LIMIT and ORDER BY clauses (see -Q option).
In addition, for incremental loading, you can define in the DatabaseUtils file how many distinct values a nominal attribute is allowed to have. If this number is exceeded, the column will become a string attribute.
In batch mode no string attributes will be created.
Valid options are:
```
 -url <JDBC URL>
  The JDBC URL to connect to.
  (default: from DatabaseUtils.props file)
 
```
```
 -user <name>
  The user to connect with to the database.
  (default: none)
 
```
```
 -password <password>
  The password to connect with to the database.
  (default: none)
 
```
```
 -Q <query>
  SQL query of the form
   SELECT <list of columns>|* FROM <table> [WHERE]
  to execute.
  (default: Select * From Results0)
 
```
```
 -P <list of column names>
  List of column names uniquely defining a DB row
  (separated by ', ').
  Used for incremental loading.
  If not specified, the key will be determined automatically,
  if possible with the used JDBC driver.
  The auto ID column created by the DatabaseSaver won't be loaded.
 
```
```
 -I
  Sets incremental loading
 
```
Version:

$Revision: 12418 $

Author:

Stefan Mutter (mutter@cs.waikato.ac.nz)

See Also:

Loader, Serialized Form

Nested Class Summary
- Nested classes/interfaces inherited from interface weka.core.converters.Loader
  Loader.StructureNotReadyException

Field Summary
- Fields inherited from interface weka.core.converters.Loader
  BATCH, INCREMENTAL, NONE

Constructor Summary

Constructors
Constructor and Description

DatabaseLoader()
Constructor

Constructors
Constructor and Description
`DatabaseLoader()` Constructor

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`connectToDatabase()` Opens a connection to the database
`java.lang.String`	`customPropsFileTipText()` The tip text for this property.
`java.io.File`	`getCustomPropsFile()` Returns the custom properties file in use, if any.
`Instances`	`getDataSet()` Return the full data set in batch mode (header and all intances at once).
`java.lang.String`	`getKeys()` Gets the key columns' name
`Instance`	`getNextInstance(Instances structure)` Read the data set incrementally---get the next instance in the data set or returns null if there are no more instances to get.
`java.lang.String[]`	`getOptions()` Gets the setting
`java.lang.String`	`getPassword()` Returns the database password
`java.lang.String`	`getQuery()` Gets the query to execute against the database
`java.lang.String`	`getRevision()` Returns the revision string.
`boolean`	`getSparseData()` Gets whether data is to be returned as a set of sparse instances
`Instances`	`getStructure()` Determines and returns (if possible) the structure (internally the header) of the data set as an empty set of instances.
`java.lang.String`	`getUrl()` Gets the URL
`java.lang.String`	`getUser()` Gets the user name
`java.lang.String`	`globalInfo()` Returns a string describing this Loader
`java.lang.String`	`keysTipText()` the tip text for this property
`java.util.Enumeration<Option>`	`listOptions()` Lists the available options
`static void`	`main(java.lang.String[] options)` Main method.
`java.lang.String`	`passwordTipText()` the tip text for this property
`java.lang.String`	`queryTipText()` the tip text for this property
`void`	`reset()` Resets the Loader ready to read a new data set using set options
`void`	`resetOptions()` Resets the Loader to the settings in either the default DatabaseUtils.props or any property file that the user has specified via setCustomPropsFile().
`void`	`resetStructure()` Resets the structure of instances
`void`	`setCustomPropsFile(java.io.File value)` Sets the custom properties file to use.
`void`	`setEnvironment(Environment env)` Set the environment variables to use.
`void`	`setKeys(java.lang.String keys)` Sets the key columns of a database table
`void`	`setOptions(java.lang.String[] options)` Sets the options.
`void`	`setPassword(java.lang.String password)` Sets user password for the database
`void`	`setQuery(java.lang.String q)` Sets the query to execute against the database
`void`	`setSource()` Sets the database url using the DatabaseUtils file
`void`	`setSource(java.lang.String url)` Sets the database url
`void`	`setSource(java.lang.String url, java.lang.String userName, java.lang.String password)` Sets the database url, user and pw
`void`	`setSparseData(boolean s)` Sets whether data should be encoded as sparse instances
`void`	`setUrl(java.lang.String url)` Sets the database URL
`void`	`setUser(java.lang.String user)` Sets the database user
`java.lang.String`	`sparseDataTipText()` Returns the tip text for this property
`java.lang.String`	`urlTipText()` the tip text for this property
`java.lang.String`	`userTipText()` the tip text for this property

Methods inherited from class weka.core.converters.AbstractLoader
setRetrieval, setSource, setSource

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

Methods inherited from interface weka.core.OptionHandler
makeCopy

- Constructor Detail
  - DatabaseLoader
```
public DatabaseLoader()
               throws java.lang.Exception
```
    Constructor
    
    Throws:
    
    java.lang.Exception - if initialization fails
- Method Detail
  - globalInfo
```
public java.lang.String globalInfo()
```
    Returns a string describing this Loader
    
    Returns:
    
    a description of the Loader suitable for displaying in the explorer/experimenter gui
  - setEnvironment
```
public void setEnvironment(Environment env)
```
    Set the environment variables to use.
    
    Specified by:
    
    setEnvironment in interface EnvironmentHandler
    
    Parameters:
    
    env - the environment variables to use
  - resetOptions
```
public void resetOptions()
```
    Resets the Loader to the settings in either the default DatabaseUtils.props or any property file that the user has specified via setCustomPropsFile().
  - reset
```
public void reset()
```
    Resets the Loader ready to read a new data set using set options
    
    Specified by:
    
    reset in interface Loader
    
    Overrides:
    
    reset in class AbstractLoader
    
    Throws:
    
    java.lang.Exception - if an error occurs while disconnecting from the database
  - resetStructure
```
public void resetStructure()
```
    Resets the structure of instances
  - setQuery
```
public void setQuery(java.lang.String q)
```
    Sets the query to execute against the database
    
    Parameters:
    
    q - the query to execute
  - getQuery
```
@OptionMetadata(displayName="Query",
                description="The query to execute",
                displayOrder=4)
public java.lang.String getQuery()
```
    Gets the query to execute against the database
    
    Returns:
    
    the query
  - queryTipText
```
public java.lang.String queryTipText()
```
    the tip text for this property
    
    Returns:
    
    the tip text
  - setKeys
```
public void setKeys(java.lang.String keys)
```
    Sets the key columns of a database table
    
    Parameters:
    
    keys - a String containing the key columns in a comma separated list.
  - getKeys
```
@OptionMetadata(displayName="Key columns",
                description="Specific key columns to use if a primary key cannot be automatically detected. Used in incremental loading.",
                displayOrder=5)
public java.lang.String getKeys()
```
    Gets the key columns' name
    
    Returns:
    
    name of the key columns'
  - keysTipText
```
public java.lang.String keysTipText()
```
    the tip text for this property
    
    Returns:
    
    the tip text
  - setCustomPropsFile
```
public void setCustomPropsFile(java.io.File value)
```
    Sets the custom properties file to use.
    
    Parameters:
    
    value - the custom props file to load database parameters from, use null or directory to disable custom properties.
  - getCustomPropsFile
```
@OptionMetadata(displayName="DB config file",
                description="The custom properties that the user can use to override the default ones.",
                displayOrder=8)
 @FilePropertyMetadata(fileChooserDialogType=0,
                      directoriesOnly=false)
public java.io.File getCustomPropsFile()
```
    Returns the custom properties file in use, if any.
    
    Returns:
    
    the custom props file, null if none used
  - customPropsFileTipText
```
public java.lang.String customPropsFileTipText()
```
    The tip text for this property.
    
    Returns:
    
    the tip text
  - setUrl
```
public void setUrl(java.lang.String url)
```
    Sets the database URL
    
    Specified by:
    
    setUrl in interface DatabaseConverter
    
    Parameters:
    
    url - string with the database URL
  - getUrl
```
@OptionMetadata(displayName="Database URL",
                description="The URL of the database",
                displayOrder=1)
public java.lang.String getUrl()
```
    Gets the URL
    
    Specified by:
    
    getUrl in interface DatabaseConverter
    
    Returns:
    
    the URL
  - urlTipText
```
public java.lang.String urlTipText()
```
    the tip text for this property
    
    Returns:
    
    the tip text
  - setUser
```
public void setUser(java.lang.String user)
```
    Sets the database user
    
    Specified by:
    
    setUser in interface DatabaseConverter
    
    Parameters:
    
    user - the database user name
  - getUser
```
@OptionMetadata(displayName="Username",
                description="The user name for the database",
                displayOrder=2)
public java.lang.String getUser()
```
    Gets the user name
    
    Specified by:
    
    getUser in interface DatabaseConverter
    
    Returns:
    
    name of database user
  - userTipText
```
public java.lang.String userTipText()
```
    the tip text for this property
    
    Returns:
    
    the tip text
  - setPassword
```
public void setPassword(java.lang.String password)
```
    Sets user password for the database
    
    Specified by:
    
    setPassword in interface DatabaseConverter
    
    Parameters:
    
    password - the password
  - getPassword
```
@OptionMetadata(displayName="Password",
                description="The database password",
                displayOrder=3)
 @PasswordProperty
public java.lang.String getPassword()
```
    Returns the database password
    
    Returns:
    
    the database password
  - passwordTipText
```
public java.lang.String passwordTipText()
```
    the tip text for this property
    
    Returns:
    
    the tip text
  - sparseDataTipText
```
public java.lang.String sparseDataTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setSparseData
```
public void setSparseData(boolean s)
```
    Sets whether data should be encoded as sparse instances
    
    Parameters:
    
    s - true if data should be encoded as a set of sparse instances
  - getSparseData
```
@OptionMetadata(displayName="Create sparse instances",
                description="Return sparse rather than normal instances",
                displayOrder=6)
public boolean getSparseData()
```
    Gets whether data is to be returned as a set of sparse instances
    
    Returns:
    
    true if data is to be encoded as sparse instances
  - setSource
```
public void setSource(java.lang.String url,
                      java.lang.String userName,
                      java.lang.String password)
```
    Sets the database url, user and pw
    
    Parameters:
    
    url - the database url
    
    userName - the user name
    
    password - the password
  - setSource
```
public void setSource(java.lang.String url)
```
    Sets the database url
    
    Parameters:
    
    url - the database url
  - setSource
```
public void setSource()
               throws java.lang.Exception
```
    Sets the database url using the DatabaseUtils file
    
    Throws:
    
    java.lang.Exception - if something goes wrong
  - connectToDatabase
```
public void connectToDatabase()
```
    Opens a connection to the database
  - getStructure
```
public Instances getStructure()
                       throws java.io.IOException
```
    Determines and returns (if possible) the structure (internally the header) of the data set as an empty set of instances.
    
    Specified by:
    
    getStructure in interface Loader
    
    Specified by:
    
    getStructure in class AbstractLoader
    
    Returns:
    
    the structure of the data set as an empty set of Instances
    
    Throws:
    
    java.io.IOException - if an error occurs
  - getDataSet
```
public Instances getDataSet()
                     throws java.io.IOException
```
    Return the full data set in batch mode (header and all intances at once).
    
    Specified by:
    
    getDataSet in interface Loader
    
    Specified by:
    
    getDataSet in class AbstractLoader
    
    Returns:
    
    the structure of the data set as an empty set of Instances
    
    Throws:
    
    java.io.IOException - if there is no source or parsing fails
  - getNextInstance
```
public Instance getNextInstance(Instances structure)
                         throws java.io.IOException
```
    Read the data set incrementally---get the next instance in the data set or returns null if there are no more instances to get. If the structure hasn't yet been determined by a call to getStructure then method does so before returning the next instance in the data set.
    
    Specified by:
    
    getNextInstance in interface Loader
    
    Specified by:
    
    getNextInstance in class AbstractLoader
    
    Parameters:
    
    structure - the dataset header information, will get updated in case of string or relational attributes
    
    Returns:
    
    the next instance in the data set as an Instance object or null if there are no more instances to be read
    
    Throws:
    
    java.io.IOException - if there is an error during parsing
  - getOptions
```
public java.lang.String[] getOptions()
```
    Gets the setting
    
    Specified by:
    
    getOptions in interface OptionHandler
    
    Returns:
    
    the current setting
  - listOptions
```
public java.util.Enumeration<Option> listOptions()
```
    Lists the available options
    
    Specified by:
    
    listOptions in interface OptionHandler
    
    Returns:
    
    an enumeration of the available options
  - setOptions
```
public void setOptions(java.lang.String[] options)
                throws java.lang.Exception
```
    Sets the options. Valid options are:
```
 -url <JDBC URL>
  The JDBC URL to connect to.
  (default: from DatabaseUtils.props file)
 
```
```
 -user <name>
  The user to connect with to the database.
  (default: none)
 
```
```
 -password <password>
  The password to connect with to the database.
  (default: none)
 
```
```
 -Q <query>
  SQL query of the form
   SELECT <list of columns>|* FROM <table> [WHERE]
  to execute.
  (default: Select * From Results0)
 
```
```
 -P <list of column names>
  List of column names uniquely defining a DB row
  (separated by ', ').
  Used for incremental loading.
  If not specified, the key will be determined automatically,
  if possible with the used JDBC driver.
  The auto ID column created by the DatabaseSaver won't be loaded.
 
```
```
 -I
  Sets incremental loading
 
```
    Specified by:
    
    setOptions in interface OptionHandler
    
    Parameters:
    
    options - the options
    
    Throws:
    
    java.lang.Exception - if options cannot be set
  - getRevision
```
public java.lang.String getRevision()
```
    Returns the revision string.
    
    Specified by:
    
    getRevision in interface RevisionHandler
    
    Returns:
    
    the revision
  - main
```
public static void main(java.lang.String[] options)
```
    Main method.
    
    Parameters:
    
    options - the options

Class DatabaseLoader

Nested Class Summary

Nested classes/interfaces inherited from interface weka.core.converters.Loader

Field Summary

Fields inherited from interface weka.core.converters.Loader

Constructor Summary

Method Summary

Methods inherited from class weka.core.converters.AbstractLoader

Methods inherited from class java.lang.Object

Methods inherited from interface weka.core.OptionHandler

Constructor Detail

DatabaseLoader

Method Detail

globalInfo

setEnvironment

resetOptions

reset

resetStructure

setQuery

getQuery

queryTipText

setKeys

getKeys

keysTipText

setCustomPropsFile

getCustomPropsFile

customPropsFileTipText

setUrl

getUrl

urlTipText

setUser

getUser

userTipText

setPassword

getPassword

passwordTipText

sparseDataTipText

setSparseData

getSparseData

setSource

setSource

setSource

connectToDatabase

getStructure

getDataSet

getNextInstance

getOptions

listOptions

setOptions

getRevision

main