net.sf.basedb.core.query
Class ExpressionSelect

java.lang.Object
  net.sf.basedb.core.query.ExpressionSelect

All Implemented Interfaces:

QueryElement, Select

public class ExpressionSelect
extends Object
implements Select

A selection query element that selects an expression, optionally giving it an alias.

SELECT <expression> AS <alias>
FROM ...

Version:

2.0

Author:

Nicklas

See Also:

Selects.expression(Expression, String)

Last modified

$Date: 2010-04-21 11:48:29 +0200 (Wed, 21 Apr 2010) $

Field Summary

private String	alias
private Expression	e1
private boolean	useInDistinctCount

Constructor Summary

ExpressionSelect(Expression e1, String alias, boolean useInDistinctCount)

Method Summary

boolean	equals(Object other) This expression is equal to another ExpressionSelect if their child expressions and aliases are equal.
String	getAlias() Get the alias of the selected expression.
Collection<? extends QueryElement>	getChildren() Get the children of this query element or null if it has no children.
Expression	getExpression() Get the expression object representing the selected expression.
int	hashCode()
String	toQl(Query query, DbControl dc) Create a query language string of the query element.
String	toString()
boolean	useInDistinctCount() If this expression should be use in count distinct queries or not.

Methods inherited from class java.lang.Object

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

Field Detail

e1

private final Expression e1

alias

private final String alias

useInDistinctCount

private final boolean useInDistinctCount

Constructor Detail

ExpressionSelect

ExpressionSelect(Expression e1,
                 String alias,
                 boolean useInDistinctCount)

Method Detail

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:

The expressions to select

getAlias

public String getAlias()

Description copied from interface: Select

Get the alias of the selected expression.

Specified by:

getAlias in interface Select

Returns:

The alias, or null if no alias has been specified

getExpression

public Expression getExpression()

Description copied from interface: Select

Get the expression object representing the selected expression.

Specified by:

getExpression in interface Select

Returns:

An expression object

useInDistinctCount

public boolean useInDistinctCount()

Description copied from interface: Select

If this expression should be use in count distinct queries or not.

SELECT COUNT(DISTINCT expression)

Specified by:

useInDistinctCount in interface Select

Returns:

TRUE or FALSE

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object other)

This expression is equal to another ExpressionSelect if their child expressions and aliases are equal.

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object