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

Class DBCountExpr

java.lang.Object

org.apache.empire.db.DBObject

org.apache.empire.db.DBExpr

org.apache.empire.db.DBColumnExpr

org.apache.empire.db.expr.column.DBCountExpr

All Implemented Interfaces:

ColumnExpr

public class DBCountExpr
extends DBColumnExpr

This class is used to add the "count" statement to the SQL-Command.

There is no need to explicitly create instances of this class.
Instead use or @link DBColumnExpr#count()

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
DBCountExpr(DBColumnExpr expr, boolean distinct)	Constructs a DBCountExpr.
DBCountExpr(DBRowSet rowset)	Constructs a DBCountExpr.

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 String "count(*)" to the SQL-Command.
Element	addXml(Element parent, long flags)	this adds the column description to the parent element
boolean	equals(Object other)	Returns true if other is equal to this expression
final DBDatabase	getDatabase()	Returns the current DBDatabase object.
DataType	getDataType()	Returns the data type: DT_INTEGER.
Class<Enum<?>>	getEnumType()	Not an Enum.
String	getName()	Returns the String "count".
DBRowSet	getRowSet()	Returns the underlying rowset
DBColumn	getUpdateColumn()	Returns the underlying column
boolean	isAggregate()	Returns true since the count function is an aggregate function.

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, toString, 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

DBCountExpr

public DBCountExpr(DBRowSet rowset)

Constructs a DBCountExpr.

Parameters:

rowset - the rowset

DBCountExpr

public DBCountExpr(DBColumnExpr expr,
 boolean distinct)

Constructs a DBCountExpr.

Parameters:

expr - the column

distinct - set true for distinct count

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: DT_INTEGER.

Specified by:

getDataType in interface ColumnExpr

Specified by:

getDataType in class DBColumnExpr

Returns:

the data type: DT_INTEGER

See Also:

• DataType

getEnumType

public Class<Enum<?>> getEnumType()

Not an Enum. Returns null

Returns:

the enum type

getName

public String getName()

Returns the String "count".

Specified by:

getName in interface ColumnExpr

Specified by:

getName in class DBColumnExpr

Returns:

the String "count"

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 underlying column

Specified by:

getUpdateColumn in interface ColumnExpr

Specified by:

getUpdateColumn in class DBColumnExpr

Returns:

the underlying column

isAggregate

public boolean isAggregate()

Returns true since the count function is an aggregate function.

Specified by:

isAggregate in class DBColumnExpr

Returns:

always true

equals

public boolean equals(Object other)

Returns true if other is equal to this expression

Overrides:

equals in class Object

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 String "count(*)" to the SQL-Command.

Specified by:

addSQL in class DBExpr

Parameters:

sql - the SQL-Command

context - the current SQL-Command context

addXml

public Element addXml(Element parent,
 long flags)

this adds the column description to the parent element

Specified by:

addXml in class DBColumnExpr

Parameters:

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

flags - currently not used

Returns:

the newly created child element