diff --git a/lang/en/error.php b/lang/en/error.php
index f9c0f3a18dd..4e5537a8ff3 100755
--- a/lang/en/error.php
+++ b/lang/en/error.php
@@ -186,6 +186,7 @@ $string['ddldependencyerror'] = '{$a->targettype} "{$a->targetname}" cannot be m
 $string['ddlexecuteerror'] = 'DDL sql execution error';
 $string['ddlfieldalreadyexists'] = 'Field "{$a}" already exists';
 $string['ddlfieldnotexist'] = 'Field "{$a->fieldname}" does not exist in table "{$a->tablename}"';
+$string['ddsequenceerror'] = 'Incorrect table "{$a}" definition; there can be only one auto column and it must be defined as a key.';
 $string['ddltablealreadyexists'] = 'Table "{$a}" already exists';
 $string['ddltablenotexist'] = 'Table "{$a}" does not exist';
 $string['ddlunknownerror'] = 'Unknown DDL library error';
diff --git a/lib/ddl/sql_generator.php b/lib/ddl/sql_generator.php
index 615cfc8474d..515e7f51d64 100644
--- a/lib/ddl/sql_generator.php
+++ b/lib/ddl/sql_generator.php
@@ -233,8 +233,13 @@ abstract class sql_generator {
             return $results;
         }
 
+        $sequencefield = null;
+
     /// Add the fields, separated by commas
         foreach ($xmldb_fields as $xmldb_field) {
+            if ($xmldb_field->getSequence()) {
+                $sequencefield = $xmldb_field->getName();
+            }
             $table .= "\n    " . $this->getFieldSQL($xmldb_field);
             $table .= ',';
         }
@@ -252,8 +257,20 @@ abstract class sql_generator {
                         $table .= "\nCONSTRAINT " . $keytext . ',';
                     }
                 }
+            /// make sure sequence field is unique
+                if ($sequencefield and $xmldb_key->getType() == XMLDB_KEY_PRIMARY) {
+                    $field = reset($xmldb_key->getFields());
+                    if ($sequencefield === $field) {
+                        $sequencefield = null;
+                    }
+                }
             }
         }
+    /// throw error if sequence field does not have unique key defined
+        if ($sequencefield) {
+            throw new ddl_exception('ddsequenceerror', $xmldb_table->getName());
+        }
+
     /// Table footer, trim the latest comma
         $table = trim($table,',');
         $table .= "\n)";