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/SelectExpression.class.php

@@ -0,0 +1,32 @@
+<?php 
+
+	/**
+	 * @class SelectExpression
+	 * @author Arnia Software
+	 * @brief Represents an expresion that appears in the select clause
+	 * 
+	 * @remarks  
+	 * 		$column_name can be:
+	 *  		- a table column name
+	 *  		- an sql function - like count(*)
+	 *	  		- an sql expression - substr(column_name, 1, 8) or score1 + score2
+	 *		$column_name is already escaped
+	 */
+
+	class SelectExpression extends Expression {
+		var $column_alias;
+		
+		function SelectExpression($column_name, $alias = NULL){
+			parent::Expression($column_name);
+			$this->column_alias = $alias;
+		}
+		
+		function getExpression() {
+			return sprintf("%s%s", $this->column_name, $this->column_alias ? " as ".$this->column_alias : "");
+		}
+		
+		function show() {
+			return true;
+		}
+	}
+?>