org.apache.empire.db.expr.column
Class DBCalcExpr

java.lang.Object
  extended by org.apache.empire.db.DBObject
      extended by org.apache.empire.db.DBExpr
          extended by org.apache.empire.db.DBColumnExpr
              extended by org.apache.empire.db.expr.column.DBCalcExpr
All Implemented Interfaces:
Serializable, ColumnExpr

public class DBCalcExpr
extends DBColumnExpr

This class is used for performing calculations in SQL
It handles the mathematical operations ("+", "-", "*", "/") for the current column.

There is no need to explicitly create instances of this class.
Instead use DBColumnExpr.plus(Object), DBColumnExpr.minus(Object), DBColumnExpr.multiplyWith(Object), DBColumnExpr.divideBy(Object)

See Also:
Serialized Form

Field Summary
 
Fields inherited from class org.apache.empire.db.DBColumnExpr
attributes, beanPropertyName, DBCOLATTR_TITLE, DBCOLATTR_TYPE, options
 
Fields inherited from class org.apache.empire.db.DBExpr
CTX_ALIAS, CTX_ALL, CTX_DEFAULT, CTX_FULLNAME, CTX_NAME, CTX_NOPARENTHESES, CTX_VALUE
 
Constructor Summary
DBCalcExpr(DBColumnExpr expr, String op, Object value)
          Constructs a DBCalcExpr object Sets the mathematical operations ("+", "-", "*", "/")
for the specified DBColumnExpr object and value.
 
Method Summary
 void addReferencedColumns(Set<DBColumn> list)
          Internal function to obtain all DBColumnExpr-objects used by this expression.
 void addSQL(StringBuilder buf, long context)
          Creates the SQL-Command adds the mathematical operations for the specified DBColumnExpr object and value to the.
 Element addXml(Element parent, long flags)
          This function set the specified mathematical operations to the XML tag.
 DBDatabase getDatabase()
          Returns the current DBDatabase object.
 DataType getDataType()
          Returns the data type: DBDataType.DECIMAL.
 String getName()
          Returns the given expression name.
 DBColumn getUpdateColumn()
          returns null
 boolean isAggregate()
          Always returns false since CalcExpressions cannot be aggregates.
 String toString()
           
 
Methods inherited from class org.apache.empire.db.DBColumnExpr
abs, append, as, as, asc, avg, cmp, coalesce, convertTo, convertTo, count, countDistinct, day, decode, decode, decode, decode, decode, decode, desc, detectDataType, divideBy, getAttribute, getBeanPropertyName, getControlType, getExprFromPhrase, getExprFromPhrase, getOptions, getSourceColumn, getTitle, in, indexOf, indexOf, indexOf, is, isBetween, isGreaterThan, isLessOrEqual, isMoreOrEqual, isNot, isNotBetween, isSmallerThan, length, like, like, likeLower, likeUpper, lower, max, min, minus, minus, month, multiplyWith, notIn, notLike, nvl, parenthesis, plus, plus, replace, reverse, round, setAttribute, setBeanPropertyName, setControlType, setOptions, setTitle, substring, substring, substring, substring, substring, substring, sum, toChar, toChar, trim, trimLeft, trimRight, trunc, upper, when, year
 
Methods inherited from class org.apache.empire.db.DBExpr
getObjectValue, getValueClass
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

DBCalcExpr

public DBCalcExpr(DBColumnExpr expr,
                  String op,
                  Object value)
Constructs a DBCalcExpr object Sets the mathematical operations ("+", "-", "*", "/")
for the specified DBColumnExpr object and value.

Parameters:
expr - an DBColumnExpr object, one column
op - the mathematical operation ("+", "-", "*" or "/")
value - the multiply, divide, summate or subtract value
Method Detail

getDatabase

public 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: DBDataType.DECIMAL.

Specified by:
getDataType in interface ColumnExpr
Specified by:
getDataType in class DBColumnExpr
Returns:
the expressions data type
See Also:
DataType

getName

public String getName()
Returns the given expression name.

Specified by:
getName in interface ColumnExpr
Specified by:
getName in class DBColumnExpr
Returns:
the column name

addXml

public Element addXml(Element parent,
                      long flags)
This function set the specified mathematical operations 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 mathematical operations)

getUpdateColumn

public DBColumn getUpdateColumn()
returns null

Specified by:
getUpdateColumn in class DBColumnExpr
Returns:
the column to be used for updates if any.

isAggregate

public boolean isAggregate()
Always returns false since CalcExpressions cannot be aggregates.

Specified by:
isAggregate in class DBColumnExpr
Returns:
false

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(StringBuilder buf,
                   long context)
Creates the SQL-Command adds the mathematical operations for the specified DBColumnExpr object and value to the. SQL-Command

Specified by:
addSQL in class DBExpr
Parameters:
buf - the SQL statment
context - the current SQL-Command context

toString

public String toString()
Overrides:
toString in class Object


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