Package org.apache.empire.db.expr.column

Class DBAliasExpr

java.lang.Object

org.apache.empire.db.DBObject

org.apache.empire.db.DBExpr

org.apache.empire.db.DBColumnExpr

org.apache.empire.db.expr.column.DBAliasExpr

All Implemented Interfaces:

Unwrappable<DBColumnExpr>, ColumnExpr, DBPreparable

public class DBAliasExpr
extends DBColumnExpr
implements DBPreparable, Unwrappable<DBColumnExpr>

This class allows column renaming in SQL.

There is no need to explicitly create instances of this class.
Instead use DBColumnExpr.as(String)

Field Summary

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

attributes, beanPropertyName, options

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

CTX_ALIAS, CTX_ALL, CTX_DEFAULT, CTX_FULLNAME, CTX_NAME, CTX_NOPARENTHESIS, CTX_VALUE

Constructor Summary

Constructors

Constructor	Description
DBAliasExpr(DBColumnExpr expr, String alias)	Constructs a DBAliasExpr object combine the DBColumnExpr object with the alias name.

Method Summary

Modifier and Type	Method	Description
void	addReferencedColumns(Set<DBColumn> list)	Internal function to obtain all DBColumnExpr-objects used by this expression.
void	addSQL(DBSQLBuilder sql, long context)	Creates the SQL-Command adds the alias name to the SQL-Command.
Element	addXml(Element parent, long flags)	This function set the alias name to the XML tag.
boolean	equals(Object other)	Overrides the equals method
final DBDatabase	getDatabase()	Returns the current DBDatabase object.
DataType	getDataType()	Returns the data type of the DBColumnExpr object.
Class<Enum<?>>	getEnumType()	Returns the enum type of this Expression (if any)
String	getName()	This helper function returns the alias name.
DBRowSet	getRowSet()	Returns the underlying rowset
DBColumn	getUpdateColumn()	Returns the DBColunm object.
boolean	isAggregate()	Forward to expression
boolean	isWrapper()	Indicates that we are actually an expression wrapper
void	prepareParams(DBCommand cmd, DBExpr parent)	Prepares an expression for a query This function is called by DBCommand in order to add values as query parameters instead of being literally included in the sql statement Please Note: This function is internally called.
String	toString()	Overrides the toString method.
DBColumnExpr	unwrap()	Returns the underlying column expression.

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

abs, aggregate, append, as, as, asc, avg, ceiling, cmp, coalesce, concat, concat, contains, convertTo, convertTo, count, countDistinct, day, decode, decode, decode, decode, decode, decode, decodeEnum, decodeSort, desc, divideBy, floor, format, function, getAttribute, getAttribute, getBeanPropertyName, getControlType, getDefaultSortOrder, getExprFromPhrase, getExprFromPhrase, getIgnoreCaseExpr, getJavaType, getNumberType, getOptions, getSourceColumn, getTitle, in, in, in, indexOf, indexOf, indexOf, is, isBetween, isCaseSensitive, isGreaterThan, isLessOrEqual, isLiteralValue, isMoreOrEqual, isNot, isNotBetween, isSmallerThan, length, like, like, likeLower, likeUpper, lower, max, min, minus, minus, modulo, month, multiplyWith, notContains, notIn, notIn, notIn, notLike, nvl, on, parenthesis, plus, plus, prepend, qualified, replace, reverse, round, setAttribute, setBeanPropertyName, setControlType, setDefaultSortOrder, setOptions, setTitle, stringAgg, stringAgg, substring, substring, substring, substring, substring, substring, sum, toChar, toChar, trim, trimLeft, trimRight, trunc, upper, when, year

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

checkParamNull

Methods inherited from class java.lang.Object

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

Constructor Details

DBAliasExpr

public DBAliasExpr(DBColumnExpr expr,
 String alias)

Constructs a DBAliasExpr object combine the DBColumnExpr object with the alias name.

Parameters:

expr - an DBColumnExpr object, one column

alias - the alias name of the column

Method Details

getDatabase

public final DBDatabase getDatabase()

Returns the current DBDatabase object.

Specified by:

getDatabase in class DBObject

Returns:

the current DBDatabase object

getDataType

public DataType getDataType()

Returns the data type of the DBColumnExpr object.

Specified by:

getDataType in interface ColumnExpr

Specified by:

getDataType in class DBColumnExpr

Returns:

the data type

See Also:

• DataType

getEnumType

public Class<Enum<?>> getEnumType()

Returns the enum type of this Expression (if any)

Specified by:

getEnumType in interface ColumnExpr

Returns:

the enum type or null

getName

public String getName()

This helper function returns the alias name.

Specified by:

getName in interface ColumnExpr

Specified by:

getName in class DBColumnExpr

Returns:

the alias name

getRowSet

public DBRowSet getRowSet()

Returns the underlying rowset

Specified by:

getRowSet in class DBColumnExpr

Returns:

a column used for this expression

getUpdateColumn

public DBColumn getUpdateColumn()

Returns the DBColunm object.

Specified by:

getUpdateColumn in interface ColumnExpr

Specified by:

getUpdateColumn in class DBColumnExpr

Returns:

the DBColunm object

isWrapper

public boolean isWrapper()

Indicates that we are actually an expression wrapper

Specified by:

isWrapper in interface Unwrappable<DBColumnExpr>

Returns:

true

unwrap

public DBColumnExpr unwrap()

Returns the underlying column expression.

Specified by:

unwrap in interface Unwrappable<DBColumnExpr>

Returns:

the underlying column expression

isAggregate

public boolean isAggregate()

Forward to expression

Specified by:

isAggregate in class DBColumnExpr

Returns:

false

equals

public boolean equals(Object other)

Overrides the equals method

Overrides:

equals in class Object

Returns:

true if alias name and expression match

prepareParams

public void prepareParams(DBCommand cmd,
 DBExpr parent)

Description copied from interface: DBPreparable

Prepares an expression for a query This function is called by DBCommand in order to add values as query parameters instead of being literally included in the sql statement Please Note: This function is internally called. Do not call yourself!

Specified by:

prepareParams in interface DBPreparable

Parameters:

cmd - the command to which to add the parameters

parent - the parent expression holding the value

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(DBSQLBuilder sql,
 long context)

Creates the SQL-Command adds the alias name to the SQL-Command.

Specified by:

addSQL in class DBExpr

Parameters:

sql - the SQL statment

context - the current SQL-Command context

addXml

public Element addXml(Element parent,
 long flags)

This function set the alias name to the XML tag.

Specified by:

addXml in class DBColumnExpr

Parameters:

parent - the parent element to which to append the column description

flags - currently not used

Returns:

the XML tag (with the alias name)

toString

public String toString()

Overrides the toString method.

Overrides:

toString in class DBColumnExpr

Returns:

the alias name