Package net.sf.basedb.core

Class RealJoin

java.lang.Object

net.sf.basedb.core.RealJoin

All Implemented Interfaces:

Join, QueryElement

class RealJoin
extends Object
implements Join

Represents a join from one virtual table in the dynamic database to a table in the regular database or between two tables in the regular database. virtualTable vt JOIN regularTable rt ON rt.id = vt.leftColumn.

Note that the join is always done to the 'id' of the items in the regular table.

Version:

2.0

Author:

Nicklas

See Also:

• RealTable

Last modified

$Date: 2012-09-14 09:28:35 +0200 (fr, 14 sep 2012) $

Field Summary

Fields

Modifier and Type	Field	Description
private final JoinType	joinType
private final RealTable	right
private RealTable	rLeft
private String	rLeftColumn
private VirtualTable	vLeft
private VirtualColumn	vLeftColumn

Constructor Summary

Constructors

Constructor	Description
RealJoin(JoinType joinType, RealTable left, RealTable right, String leftColumn)	Create a new join between two regular tables.
RealJoin(JoinType joinType, VirtualTable left, RealTable right, VirtualColumn leftColumn)	Create a new join between a virtual and a regular table.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object other)	This join is equal to another RealJoin if they join between the same tables using the same columns and join types.
Collection<? extends QueryElement>	getChildren()	Get the children of this query element or null if it has no children.
private String	getLeftTableAlias(Query query)
private String	getLeftTableColumn()
String	getThetaJoin(Query query, DbControl dc)
String	getThetaJoinCondition(Query query, DbControl dc)
int	hashCode()
String	toQl(Query query, DbControl dc)	Create a query language string of the query element.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

joinType

private final JoinType joinType

right

private final RealTable right

vLeft

private VirtualTable vLeft

vLeftColumn

private VirtualColumn vLeftColumn

rLeft

private RealTable rLeft

rLeftColumn

private String rLeftColumn

Constructor Details

RealJoin

RealJoin(JoinType joinType,
 VirtualTable left,
 RealTable right,
 VirtualColumn leftColumn)

Create a new join between a virtual and a regular table. SELECT ... FROM left JOIN right ON right.id = left.column.

Parameters:

joinType - The type of join

left - The left table to join from, if not specified we join from the root table

right - The table to join to

leftColumn - The column in the left table to join from, we always join to the id of the real table

RealJoin

RealJoin(JoinType joinType,
 RealTable left,
 RealTable right,
 String leftColumn)

Create a new join between two regular tables. SELECT ... FROM left JOIN right ON right.id = left.column.

Parameters:

joinType - The type of join

left - The left table to join from, if not specified we join from the root table

right - The table to join to

leftColumn - The column in the left table to join from, we always join to the id of the real table

Method Details

toQl

public String toQl(Query query,
 DbControl dc)
            throws BaseException

Description copied from interface: QueryElement

Create a query language string of the query element. Use the Query.getQueryType() method to find out which query language is wanted in case the element requires different syntax for different languages.

Specified by:

toQl in interface QueryElement

Parameters:

query - The query that is about to be executed

dc - The DbControl object used to execute the query

Throws:

BaseException - If there is any other error

getChildren

public Collection<? extends QueryElement> getChildren()

Description copied from interface: QueryElement

Get the children of this query element or null if it has no children. For example the AddExpression has two children, the expression beeing added.

Specified by:

getChildren in interface QueryElement

Returns:

Always null

getThetaJoin

public String getThetaJoin(Query query,
 DbControl dc)
                    throws BaseException

Specified by:

getThetaJoin in interface Join

Throws:

BaseException

getThetaJoinCondition

public String getThetaJoinCondition(Query query,
 DbControl dc)
                             throws BaseException

Specified by:

getThetaJoinCondition in interface Join

Throws:

BaseException

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object other)

This join is equal to another RealJoin if they join between the same tables using the same columns and join types.

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getLeftTableAlias

private String getLeftTableAlias(Query query)

getLeftTableColumn

private String getLeftTableColumn()