jimm.datavision.source
Class Join

java.lang.Object
  jimm.datavision.source.Join

All Implemented Interfaces:

java.lang.Cloneable, Writeable

public class Join
extends java.lang.Object
implements Writeable, java.lang.Cloneable

A join represents the relationship between two columns in the database. It is used by a query to build the SQL string necessary to retrieve data.

Author:

Jim Menard, jimm@io.com

See Also:

Query

Field Summary

protected Column	from
protected java.lang.String	relation
static java.lang.String[]	RELATIONS
protected Column	to

Constructor Summary

Join(Column fromCol, java.lang.String relation, Column toCol)
Constructor.

Method Summary

java.lang.Object	clone()
Column	getFrom() Returns the "from" column.
java.lang.String	getRelation() Returns the relation string (for example, "=" or "<").
Column	getTo() Returns the "to" column.
void	setFrom(Column newFrom) Sets the "from" column.
void	setRelation(java.lang.String newRelation) Sets the relation string (for example, "=" or "<").
void	setTo(Column newTo) Sets the "to" column.
java.lang.String	toString() Returns a string representation of this join, usable as a where clause in a SQL query.
void	writeXML(XMLWriter out) Writes this join as an XML tag.

Methods inherited from class java.lang.Object

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

Field Detail

RELATIONS

public static final java.lang.String[] RELATIONS

from

protected Column from

relation

protected java.lang.String relation

to

protected Column to

Constructor Detail

Join

public Join(Column fromCol,
            java.lang.String relation,
            Column toCol)

Constructor.

Parameters:

fromCol - a database column

relation - a string like "=" or "<" used to join the two database columns

toCol - another database column

See Also:

Column

Method Detail

clone

public java.lang.Object clone()

Overrides:

clone in class java.lang.Object

getFrom

public Column getFrom()

Returns the "from" column.

Returns:

a column

setFrom

public void setFrom(Column newFrom)

Sets the "from" column.

Parameters:

newFrom - the new column

getRelation

public java.lang.String getRelation()

Returns the relation string (for example, "=" or "<").

Returns:

a string used to define the relationship between the two database columns

setRelation

public void setRelation(java.lang.String newRelation)

Sets the relation string (for example, "=" or "<").

Parameters:

newRelation - the new string

getTo

public Column getTo()

Returns the "to" column.

Returns:

a column

setTo

public void setTo(Column newTo)

Sets the "to" column.

Parameters:

newTo - the new column

toString

public java.lang.String toString()

Returns a string representation of this join, usable as a where clause in a SQL query.

Overrides:

toString in class java.lang.Object

writeXML

public void writeXML(XMLWriter out)

Writes this join as an XML tag.

Specified by:

writeXML in interface Writeable

Parameters:

out - a writer that knows how to write XML