diff --git a/routeSQL.php b/routeSQL.php
index e4525b1..970d0d8 100644
--- a/routeSQL.php
+++ b/routeSQL.php
@@ -772,6 +772,11 @@ class routeSQL
         $content .= ".routeSQL table .action .edit { color:#222; font-weight:bolder;}\n";
         $content .= ".routeSQL table .action .delete { color:#c00; font-weight:bolder; }\n";
         $content .= ".routeSQL table .odd { background-color:#f9f9f9; }\n";
+        $content .= ".routeSQL .alert { border-radius: 4px ; border-width: 1px; padding:10px; }\n";
+        $content .= ".routeSQL .alert-success { border-color: #d6e9c6; background-color: #dff0d8; color: #3c763d}\n";
+        $content .= ".routeSQL .alert-info { border-color: #bce8f1; background-color: #d9edf7; color: #31708f;}\n";
+        $content .= ".routeSQL .alert-warning { border-color: #faebcc; background-color: #fcf8e3; color: #8a6d3b;}\n";
+        $content .= ".routeSQL .alert-danger { border-color: #ebccd1; background-color: #f2dede; color: #a94442; }\n";
         $content .= "</style>\n";
       }
       $content .= "<div class='routeSQL'>\n";
@@ -1066,6 +1071,11 @@ class routeSQL
         $content .= "* { box-sizing: border-box;}\n";
         $content .= "button, input, optgroup, select, textarea { margin:0px 0px 0px 0px; }\n";
         $content .= "#form .form-control[disabled], #form .form-control[readonly], #form fieldset[disabled] .form-control { cursor: not-allowed; background-color: #eee; opacity: 1; }\n";
+        $content .= ".alert { border-radius: 4px ; border-width: 1px; padding:10px; }\n";
+        $content .= ".alert-success { border-color: #d6e9c6; background-color: #dff0d8; color: #3c763d}\n";
+        $content .= ".alert-info { border-color: #bce8f1; background-color: #d9edf7; color: #31708f;}\n";
+        $content .= ".alert-warning { border-color: #faebcc; background-color: #fcf8e3; color: #8a6d3b;}\n";
+        $content .= ".alert-danger { border-color: #ebccd1; background-color: #f2dede; color: #a94442; }\n";
         $content .= "</style>\n";
         // CSS is in edit an id too !
       }
@@ -1151,8 +1161,15 @@ class routeSQL
 	    $this->connect();
       $f = new form ();
       $values = $f->values ();
+      $errorsChain = array ();
+      if ($this->chainedForeign !== null &&
+          isset ($values[$this->chainedForeign]) &&
+          $values[$this->chainedForeign] !== $chain)
+        $errorsChain[$this->chainedForeign] = 
+          array ("error", dgettext("domframework",
+                                   "Can not change the external key"));
       $errors = $this->objectDB->verify ($values);
-      if (count ($errors) == 0)
+      if (count ($errors) == 0 && count ($errorsChain) == 0)
       {
         try
         {
@@ -1173,7 +1190,7 @@ class routeSQL
       else
       {
         $renderer = new renderer ();
-        foreach ($errors as $error)
+        foreach ($errorsChain as $error)
           $renderer->flash (strtoupper ($error[0]), $error[1]);
       }
       // If errors : save them and redirect to the page of editing to be
@@ -1296,6 +1313,11 @@ class routeSQL
         $content .= "* { box-sizing: border-box;}\n";
         $content .= "button, input, optgroup, select, textarea { margin:0px 0px 0px 0px; }\n";
         $content .= "#form .form-control[disabled], #form .form-control[readonly], #form fieldset[disabled] .form-control { cursor: not-allowed; background-color: #eee; opacity: 1; }\n";
+        $content .= ".alert { border-radius: 4px ; border-width: 1px; padding:10px; }\n";
+        $content .= ".alert-success { border-color: #d6e9c6; background-color: #dff0d8; color: #3c763d}\n";
+        $content .= ".alert-info { border-color: #bce8f1; background-color: #d9edf7; color: #31708f;}\n";
+        $content .= ".alert-warning { border-color: #faebcc; background-color: #fcf8e3; color: #8a6d3b;}\n";
+        $content .= ".alert-danger { border-color: #ebccd1; background-color: #f2dede; color: #a94442; }\n";
         $content .= "</style>\n";
         // CSS is in add too !
       }
@@ -1425,8 +1447,6 @@ class routeSQL
       else
       {
         $renderer = new renderer ();
-        foreach ($errors as $error)
-          $renderer->flash (strtoupper ($error[0]), $error[1]);
         foreach ($errorsChain as $error)
           $renderer->flash (strtoupper ($error[0]), $error[1]);
       }