com.caucho.db.sql

Class CountExpr

java.lang.Object

com.caucho.db.sql.Expr

com.caucho.db.sql.FunExpr

com.caucho.db.sql.CountExpr

All Implemented Interfaces:

GroupExpr

public class CountExpr
extends FunExpr
implements GroupExpr

Field Summary

Fields

Modifier and Type	Field and Description
protected static L10N	L

Fields inherited from class com.caucho.db.sql.Expr

FALSE, TRUE, UNKNOWN

Constructor Summary

Constructors

Constructor and Description
CountExpr()

Method Summary

Modifier and Type	Method and Description
protected void	addArg(Expr expr)
Expr	bind(Query query)
double	evalDouble(QueryContext context) Evaluates the expression as a double.
void	evalGroup(QueryContext context) Evaluates aggregate functions during the group phase.
long	evalLong(QueryContext context) Evaluates the expression as a long.
java.lang.String	evalString(QueryContext context) Evaluates the expression as a string.
java.lang.Class	getType() Returns the expected result type of the expression.
void	initGroup(QueryContext context) Initializes aggregate functions during the group phase.
boolean	isNull(QueryContext context) Returns true for a null value.

Methods inherited from class com.caucho.db.sql.Expr

cost, createOrder, evalBoolean, evalBytes, evalDate, evalEqual, evalEqual, evalStream, evalToBuffer, evalToBuffer, evalToResult, getIndexExpr, getName, getSQLType, getTable, getTypeCode, indexCost, indexSubCost, isBinaryStream, isBoolean, isDouble, isLong, isNullable, isParam, isSelect, splitAnd, subCost, updateDouble, updateLong, updateString

Methods inherited from class java.lang.Object

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

Field Detail

L

protected static final L10N L

Constructor Detail

CountExpr

public CountExpr()

Method Detail

addArg

protected void addArg(Expr expr)
               throws java.sql.SQLException

Specified by:

addArg in class FunExpr

Throws:

java.sql.SQLException

bind

public Expr bind(Query query)
          throws java.sql.SQLException

Overrides:

bind in class Expr

Throws:

java.sql.SQLException

getType

public java.lang.Class getType()

Returns the expected result type of the expression.

Overrides:

getType in class Expr

initGroup

public void initGroup(QueryContext context)
               throws java.sql.SQLException

Initializes aggregate functions during the group phase.

Overrides:

initGroup in class Expr

Parameters:

context - the current database tuple

Throws:

java.sql.SQLException

evalGroup

public void evalGroup(QueryContext context)
               throws java.sql.SQLException

Evaluates aggregate functions during the group phase.

Overrides:

evalGroup in class Expr

Parameters:

context - the current database tuple

Throws:

java.sql.SQLException

isNull

public boolean isNull(QueryContext context)
               throws java.sql.SQLException

Returns true for a null value.

Overrides:

isNull in class Expr

Parameters:

rows - the current tuple being evaluated

Returns:

true if null

Throws:

java.sql.SQLException

evalDouble

public double evalDouble(QueryContext context)
                  throws java.sql.SQLException

Evaluates the expression as a double.

Overrides:

evalDouble in class Expr

Parameters:

rows - the current tuple being evaluated

Returns:

the double value

Throws:

java.sql.SQLException

evalLong

public long evalLong(QueryContext context)
              throws java.sql.SQLException

Evaluates the expression as a long.

Overrides:

evalLong in class Expr

Parameters:

rows - the current tuple being evaluated

Returns:

the long value

Throws:

java.sql.SQLException

evalString

public java.lang.String evalString(QueryContext context)
                            throws java.sql.SQLException

Evaluates the expression as a string.

Overrides:

evalString in class Expr

Parameters:

rows - the current tuple being evaluated

Returns:

the string value

Throws:

java.sql.SQLException