Update new xml query classes with xe 1.5

with improved query argument support and update and delete queries

git-svn-id: http://xe-core.googlecode.com/svn/branches/1.5.0-DB@8378 201d5d3c-b55e-5fd7-737f-ddc643e51545

classes/db/queryparts/expression/Expression.class.php

@@ -0,0 +1,30 @@
+<?php
+	/**
+	 * @class Expression
+	 * @author Corina
+	 * @brief Represents an expression used in select/update/insert/delete statements
+	 * 
+	 *  Examples (expressions are inside double square brackets):
+	 *  	select [[columnA]], [[columnB as aliasB]] from tableA
+	 *  	update tableA set [[columnA = valueA]] where columnB = something
+	 *
+	 */
+
+	class Expression {
+		var $column_name;
+		
+		function Expression($column_name){
+			$this->column_name = $column_name;
+		}
+		
+		function getColumnName(){
+			return $this->column_name;
+		}
+		
+		function show() {
+			return false;
+		}
+		
+		function getExpression() {
+		}
+	}