Adding test for SortColumn to SQLQueryTest

Mostly for the benefit of MSSQLDatabase which is having problems
with subselects and alias functions.

model/SQLQuery.php

@@ -566,6 +566,7 @@ class SQLQuery {
 		if($this->orderby) {
 			$i = 0;
 			foreach($this->orderby as $clause => $dir) {
+
 				// public function calls and multi-word columns like "CASE WHEN ..."
 				if(strpos($clause, '(') !== false || strpos($clause, " ") !== false ) {
 					// remove the old orderby

tests/model/SQLQueryTest.php

@@ -368,12 +368,38 @@ class SQLQueryTest extends SapphireTest {
 		}
 	}
 
+	/**
+	 * Test that "_SortColumn0" is added for an aggregate in the ORDER BY
+	 * clause, in combination with a LIMIT and GROUP BY clause.
+	 * For some databases, like MSSQL, this is a complicated scenario
+	 * because a subselect needs to be done to query paginated data.
+	 */
+	public function testOrderByContainingAggregateAndLimitOffset() {
+		$query = new SQLQuery();
+		$query->setSelect(array('"Name"', '"Meta"'));
+		$query->setFrom('"SQLQueryTest_DO"');
+		$query->setOrderBy(array('MAX(Date)'));
+		$query->setGroupBy(array('"Name"', '"Meta"'));
+		$query->setLimit('1', '1');
+
+		$records = array();
+		foreach($query->execute() as $record) {
+			$records[] = $record;
+		}
+
+		$this->assertCount(1, $records);
+
+		$this->assertEquals('Object 2', $records[0]['Name']);
+		$this->assertEquals('2012-05-01 09:00:00', $records['0']['_SortColumn0']);
+	}
+
 }
 
 class SQLQueryTest_DO extends DataObject implements TestOnly {
 	static $db = array(
 		"Name" => "Varchar",
 		"Meta" => "Varchar",
+		"Date" => "SS_Datetime"
 	);
 }
 

tests/model/SQLQueryTest.yml

@@ -2,6 +2,8 @@ SQLQueryTest_DO:
   test1:
     Name: 'Object 1'
     Meta: 'Details 1'
+    Date: 2012-01-01 10:00:00
   test2:
     Name: 'Object 2'
-    Meta: 'Details 2'
+    Meta: 'Details 2'
+    Date: 2012-05-01 09:00:00