dk.eobjects.metamodel.query
Class SelectItem

java.lang.Object
  dk.eobjects.metamodel.query.SelectItem

All Implemented Interfaces:

IQueryItem, java.io.Serializable, java.lang.Cloneable

public class SelectItem
extends java.lang.Object
implements IQueryItem, java.lang.Cloneable

Represents a SELECT item. SelectItems can take different forms:

• column SELECTs (selects a column from a table)
• column function SELECTs (aggregates the values of a column)
• expression SELECTs (retrieves data based on an expression (only supported for JDBC datastores)
• expression function SELECTs (retrieves databased on a function and an expression, only COUNT(*) is supported for non-JDBC datastores))
• SELECTs from subqueries (works just like column selects, but in stead of pointing to a column, it retrieves data from the select item of a subquery)

See Also:

SelectClause, Serialized Form

Constructor Summary

SelectItem(Column column)
Creates a simple SelectItem that selects from a column

SelectItem(FunctionType function, Column column)
Creates a SelectItem that uses a function on a column, for example SUM(price) or MAX(age)

SelectItem(FunctionType function, java.lang.String expression, java.lang.String alias)
Creates a SelectItem based on a function and an expression.

SelectItem(SelectItem subQuerySelectItem, FromItem subQueryFromItem)
Creates a SelectItem that

SelectItem(java.lang.String expression, java.lang.String alias)
Creates a SelectItem based on an expression.

Method Summary

protected SelectItem	clone()
boolean	equals(java.lang.Object obj)
boolean	equalsIgnoreAlias(SelectItem that)
java.lang.String	getAlias()
Column	getColumn()
static SelectItem	getCountAllItem() Generates a COUNT(*) select item
java.lang.String	getExpression()
FunctionType	getFunction()
Query	getQuery()
java.lang.String	getSameQueryAlias()
FromItem	getSubQueryFromItem()
SelectItem	getSubQuerySelectItem()
java.lang.String	getSuperQueryAlias()
java.lang.String	getSuperQueryAlias(boolean includeQuotes)
int	hashCode()
static boolean	isCountAllItem(SelectItem item)
boolean	isReferenced(Column column) Investigates whether or not this SelectItem references a particular column.
SelectItem	setAlias(java.lang.String alias)
SelectItem	setColumn(Column column)
SelectItem	setExpression(java.lang.String expression)
SelectItem	setFunction(FunctionType function)
SelectItem	setQuery(Query query)
SelectItem	setSubQueryFromItem(FromItem subQueryFromItem)
SelectItem	setSubQuerySelectItem(SelectItem subQuerySelectItem)
java.lang.String	toString()
java.lang.StringBuilder	toStringNoAlias()

Methods inherited from class java.lang.Object

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

Constructor Detail

SelectItem

public SelectItem(Column column)

Creates a simple SelectItem that selects from a column

Parameters:

column -

SelectItem

public SelectItem(FunctionType function,
                  Column column)

Creates a SelectItem that uses a function on a column, for example SUM(price) or MAX(age)

Parameters:

function -

column -

SelectItem

public SelectItem(java.lang.String expression,
                  java.lang.String alias)

Creates a SelectItem based on an expression. All expression-based SelectItems must have aliases.

Parameters:

expression -

alias -

SelectItem

public SelectItem(FunctionType function,
                  java.lang.String expression,
                  java.lang.String alias)

Creates a SelectItem based on a function and an expression. All expression-based SelectItems must have aliases.

Parameters:

function -

expression -

alias -

SelectItem

public SelectItem(SelectItem subQuerySelectItem,
                  FromItem subQueryFromItem)

Creates a SelectItem that

Parameters:

subQuerySelectItem -

subQueryFromItem - the FromItem that holds the sub-query

Method Detail

getCountAllItem

public static SelectItem getCountAllItem()

Generates a COUNT(*) select item

isCountAllItem

public static boolean isCountAllItem(SelectItem item)

getAlias

public java.lang.String getAlias()

setAlias

public SelectItem setAlias(java.lang.String alias)

getFunction

public FunctionType getFunction()

setFunction

public SelectItem setFunction(FunctionType function)

getColumn

public Column getColumn()

setColumn

public SelectItem setColumn(Column column)

getExpression

public java.lang.String getExpression()

setExpression

public SelectItem setExpression(java.lang.String expression)

setQuery

public SelectItem setQuery(Query query)

Specified by:

setQuery in interface IQueryItem

getQuery

public Query getQuery()

Specified by:

getQuery in interface IQueryItem

getSubQuerySelectItem

public SelectItem getSubQuerySelectItem()

setSubQuerySelectItem

public SelectItem setSubQuerySelectItem(SelectItem subQuerySelectItem)

getSubQueryFromItem

public FromItem getSubQueryFromItem()

setSubQueryFromItem

public SelectItem setSubQueryFromItem(FromItem subQueryFromItem)

getSuperQueryAlias

public java.lang.String getSuperQueryAlias()

Returns:

the name that this SelectItem can be referenced with, if referenced from a super-query. This will usually be the alias, but if there is no alias, then the column name will be used.

getSuperQueryAlias

public java.lang.String getSuperQueryAlias(boolean includeQuotes)

Parameters:

includeQuotes - indicates whether or not the output should include quotes, if the select item's column has quotes associated (typically true, but false if used for presentation)

Returns:

the name that this SelectItem can be referenced with, if referenced from a super-query. This will usually be the alias, but if there is no alias, then the column name will be used.

getSameQueryAlias

public java.lang.String getSameQueryAlias()

Returns:

an alias that can be used in WHERE, GROUP BY and ORDER BY clauses in the same query

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

toStringNoAlias

public java.lang.StringBuilder toStringNoAlias()

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

equalsIgnoreAlias

public boolean equalsIgnoreAlias(SelectItem that)

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

clone

protected SelectItem clone()

Overrides:

clone in class java.lang.Object

isReferenced

public boolean isReferenced(Column column)

Investigates whether or not this SelectItem references a particular column. This will search for direct references and indirect references via subqueries.

Parameters:

column -

Returns:

a boolean that is true if the specified column is referenced by this SelectItem and false otherwise.