/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.empire.db.expr.column;
// Java
import java.util.Date;
import java.util.Set;
import org.apache.empire.data.DataType;
import org.apache.empire.db.DBColumn;
import org.apache.empire.db.DBColumnExpr;
import org.apache.empire.db.DBDatabase;
import org.apache.empire.db.DBExpr;
import org.w3c.dom.Element;
/**
* This class is used for performing calculations in SQL<br>
* It handles the mathematical operations ("+", "-", "*", "/") for the current column.
* <P>
* There is no need to explicitly create instances of this class.<BR>
* Instead use {@link DBColumnExpr#plus(Object) }, {@link DBColumnExpr#minus(Object) },
* {@link DBColumnExpr#multiplyWith(Object) }, {@link DBColumnExpr#divideBy(Object) }
* <P>
*/
public class DBCalcExpr extends DBColumnExpr
{
private final static long serialVersionUID = 1L;
private final DBColumnExpr expr;
private final String op;
private final Object value;
/**
* Constructs a DBCalcExpr object Sets the mathematical operations ("+", "-", "*", "/") <br>
* for the specified DBColumnExpr object and value.
*
* @param expr an DBColumnExpr object, one column
* @param op the mathematical operation ("+", "-", "*" or "/")
* @param value the multiply, divide, summate or subtract value
*/
public DBCalcExpr(DBColumnExpr expr, String op, Object value)
{
this.expr = expr;
this.value = value;
this.op = op;
}
/**
* Returns the current DBDatabase object.
*
* @return the current DBDatabase object
*/
@Override
public DBDatabase getDatabase()
{
return expr.getDatabase();
}
/**
* Returns the data type: DBDataType.DECIMAL.
*
*/
@Override
public DataType getDataType()
{
DataType type = expr.getDataType();
// Special treatment for adding days to dates
if (type.isDate())
{ // see whether the value is a date too
if ((value instanceof Date) ||
(value instanceof DBDatabase.DBSystemDate) ||
((value instanceof DBColumnExpr) && ((DBColumnExpr)value).getDataType().isDate()))
{ // Yes, result is a decimal
return DataType.DECIMAL;
}
}
else if ((value instanceof DBColumnExpr))
{ // Use the value type?
DataType type2 = ((DBColumnExpr)value).getDataType();
if (type2.isNumeric() && type2.ordinal()>type.ordinal())
return type2;
}
// type
return type;
}
/** Returns the given expression name. */
@Override
public String getName()
{ // Get the expression name
return expr.getName();
}
/**
* This function set the specified mathematical operations to the XML tag.
*
* @return the XML tag (with the mathematical operations)
*/
@Override
public Element addXml(Element parent, long flags)
{ // Add Expressions
expr.addXml(parent, flags);
// Add Vaue
if (value instanceof DBColumnExpr)
((DBColumnExpr) value).addXml(parent, flags);
// done
return parent;
}
/** returns null */
@Override
public DBColumn getUpdateColumn()
{
return null;
}
/**
* Always returns false since CalcExpressions cannot be aggregates.
*
* @return false
*/
@Override
public boolean isAggregate()
{
return false;
}
/**
* @see org.apache.empire.db.DBExpr#addReferencedColumns(Set)
*/
@Override
public void addReferencedColumns(Set<DBColumn> list)
{
expr.addReferencedColumns(list);
// Check if value is a DBExpr
if (value instanceof DBExpr)
((DBExpr)value).addReferencedColumns(list);
}
/**
* Creates the SQL-Command adds the mathematical operations for
* the specified DBColumnExpr object and value to the.
* SQL-Command
*
* @param buf the SQL statment
* @param context the current SQL-Command context
*/
@Override
public void addSQL(StringBuilder buf, long context)
{
// Zusammenbauen
expr.addSQL(buf, context);
buf.append(op);
// Special treatment for adding days to dates
DataType type = expr.getDataType();
if (type.isNumeric()==false && (value instanceof Number))
type = DataType.DECIMAL;
// append
buf.append(getObjectValue(type, value, context, op));
}
@Override
public String toString()
{ // Get a unique Name
String name = expr.toString();
name += "_X_";
name += value.toString();
// name
return name;
}
}