org.apache.empire.db.expr.join

Class DBColumnJoinExpr

java.lang.Object

org.apache.empire.db.DBObject

org.apache.empire.db.DBExpr

org.apache.empire.db.expr.join.DBJoinExpr

org.apache.empire.db.expr.join.DBColumnJoinExpr

Direct Known Subclasses:

DBCompareJoinExpr

public class DBColumnJoinExpr
extends DBJoinExpr

Field Summary

Fields

Modifier and Type	Field and Description
DBCompareExpr	compExpr
protected DBColumnExpr	left
protected DBColumnExpr	right

Fields inherited from class org.apache.empire.db.expr.join.DBJoinExpr

type

Fields inherited from class org.apache.empire.db.DBExpr

CTX_ALIAS, CTX_ALL, CTX_DEFAULT, CTX_FULLNAME, CTX_NAME, CTX_NOPARENTHESES, CTX_VALUE

Constructor Summary

Constructors

Constructor and Description
DBColumnJoinExpr(DBColumnExpr left, DBColumnExpr right, DBJoinType type) Constructs a new DBJoinExpr object initialize this object with the left and right column and the data type of the join expression.

Method Summary

Modifier and Type	Method and Description
void	addReferencedColumns(Set<DBColumn> list) Internal function to obtain all DBColumnExpr-objects used by this expression.
void	addSQL(StringBuilder buf, long context) Not allowed, this operation have to be done in the DBCommand object.
DBJoinExpr	and(DBColumnExpr c1, DBColumnExpr c2) This function adds an additional constraint to the join.
boolean	equals(Object obj) Compares two DBJoinExpr objects.
DBDatabase	getDatabase() Returns the current DBDatabase object.
DBColumnExpr	getLeft() returns the left join expression
DBRowSet	getLeftTable() returns the RowSet on the left of the join
DBRowSet	getOuterTable() Returns the left table name if the data type= JOIN_LEFT and returns the right table if the data type= JOIN_RIGHT.
DBColumnExpr	getRight() returns the right join expression
DBRowSet	getRightTable() returns the RowSet on the right of the join
Object[]	getSubqueryParams(int which) Returns the subquery Params Valid only directly after addSQL() has been called!
DBCompareExpr	getWhere() Returns any additional constraints to the join
boolean	isJoinOn(DBColumn column) returns true if this join is using the given column or false otherwise
boolean	isJoinOn(DBRowSet rowset) returns true if this join is using the given table or view or false otherwise
void	reverse() This function swaps the left and the right statements of the join expression.
void	where(DBCompareExpr expr) This function adds an additional constraint to the join.

Methods inherited from class org.apache.empire.db.expr.join.DBJoinExpr

getType, setType

Methods inherited from class org.apache.empire.db.DBExpr

getObjectValue

Methods inherited from class org.apache.empire.db.DBObject

checkParamNull

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

left

protected DBColumnExpr left

right

protected DBColumnExpr right

compExpr

public DBCompareExpr compExpr

Constructor Detail

DBColumnJoinExpr

public DBColumnJoinExpr(DBColumnExpr left,
                        DBColumnExpr right,
                        DBJoinType type)

Constructs a new DBJoinExpr object initialize this object with the left and right column and the data type of the join expression.

Parameters:

left - left value

right - right value

type - data type (JOIN_INNER, JOIN_LEFT or JOIN_RIGHT)

Method Detail

getDatabase

public final DBDatabase getDatabase()

Returns the current DBDatabase object.

Specified by:

getDatabase in class DBObject

Returns:

the current DBDatabase object

getLeft

public DBColumnExpr getLeft()

returns the left join expression

getRight

public DBColumnExpr getRight()

returns the right join expression

getLeftTable

public DBRowSet getLeftTable()

Description copied from class: DBJoinExpr

returns the RowSet on the left of the join

Specified by:

getLeftTable in class DBJoinExpr

getRightTable

public DBRowSet getRightTable()

returns the RowSet on the right of the join

Specified by:

getRightTable in class DBJoinExpr

isJoinOn

public boolean isJoinOn(DBRowSet rowset)

returns true if this join is using the given table or view or false otherwise

Specified by:

isJoinOn in class DBJoinExpr

isJoinOn

public boolean isJoinOn(DBColumn column)

returns true if this join is using the given column or false otherwise

Specified by:

isJoinOn in class DBJoinExpr

getOuterTable

public DBRowSet getOuterTable()

Returns the left table name if the data type= JOIN_LEFT and returns the right table if the data type= JOIN_RIGHT. If the data type = JOIN_INNER the return value is null.

Specified by:

getOuterTable in class DBJoinExpr

Returns:

the current DBDatabase object

reverse

public void reverse()

This function swaps the left and the right statements of the join expression.

Specified by:

reverse in class DBJoinExpr

getWhere

public DBCompareExpr getWhere()

Returns any additional constraints to the join

Returns:

a compare expression containing additional constraints or null

where

public void where(DBCompareExpr expr)

This function adds an additional constraint to the join.

Parameters:

expr - the compare expression

and

public DBJoinExpr and(DBColumnExpr c1,
                      DBColumnExpr c2)

This function adds an additional constraint to the join.

Parameters:

c1 - the first column

c2 - the second column

Returns:

the object itself

addReferencedColumns

public void addReferencedColumns(Set<DBColumn> list)

Description copied from class: DBExpr

Internal function to obtain all DBColumnExpr-objects used by this expression.

Specified by:

addReferencedColumns in class DBExpr

Parameters:

list - list to which all used column expressions must be added

See Also:

DBExpr.addReferencedColumns(Set)

addSQL

public void addSQL(StringBuilder buf,
                   long context)

Not allowed, this operation have to be done in the DBCommand object.

Specified by:

addSQL in class DBExpr

Parameters:

buf - the string buffer used to build the sql command

context - context flag for this SQL-Command (see CTX_??? constants).

getSubqueryParams

public Object[] getSubqueryParams(int which)

Returns the subquery Params Valid only directly after addSQL() has been called!

Specified by:

getSubqueryParams in class DBJoinExpr

Parameters:

which: - both (==0) | left (<=0) | right (>=0)

Returns:

the subquery params;

equals

public boolean equals(Object obj)

Compares two DBJoinExpr objects.

Overrides:

equals in class Object

Parameters:

obj - other DBJoinExpr object

Returns:

true if the other DBJoinExpr object is equal to this object