ported guid() from MDB2

lib/Doctrine/Expression.php

@@ -652,4 +652,13 @@ class Doctrine_Expression extends Doctrine_Connection_Module
         $value2 = $this->getIdentifier($value2);
         return $expression . ' BETWEEN ' .$value1 . ' AND ' . $value2;
     }
+    /**
+     * Returns global unique identifier
+     *
+     * @return string to get global unique identifier
+     */
+    public function guid()
+    {
+        throw new Doctrine_Expression_Exception('method not implemented');
+    }
 }

lib/Doctrine/Expression/Mssql.php

@@ -71,11 +71,19 @@ class Doctrine_Expression_Mssql extends Doctrine_Expression
      * @param string $arg2
      * @param string $values...
      * @return string to concatenate two strings
-     * @access public
+     */
-     **/
+    public function concat($arg1, $arg2)
-    function concat($arg1, $arg2)
     {
         $args = func_get_args();
         return '(' . implode(' + ', $args) . ')';
     }
+    /**
+     * Returns global unique identifier
+     *
+     * @return string to get global unique identifier
+     */
+    public function guid()
+    {
+        return 'NEWID()';
+    }
 }

lib/Doctrine/Expression/Mysql.php

@@ -98,4 +98,13 @@ class Doctrine_Expression_Mysql extends Doctrine_Expression
         $match.= $this->patternEscapeString();
         return $match;
     }
+    /**
+     * Returns global unique identifier
+     *
+     * @return string to get global unique identifier
+     */
+    public function guid()
+    {
+        return 'UUID()';
+    }
 }

lib/Doctrine/Expression/Oracle.php

@@ -89,8 +89,17 @@ class Doctrine_Expression_Oracle extends Doctrine_Expression
      *
      * @return string           an oracle SQL string that generates a float between 0 and 1
      */
-    function random()
+    public function random()
     {
         return 'dbms_random.value';
     }
+    /**
+     * Returns global unique identifier
+     *
+     * @return string to get global unique identifier
+     */
+    public function guid()
+    {
+        return 'SYS_GUID()';
+    }
 }