diff --git a/sql_server/pyodbc/schema.py b/sql_server/pyodbc/schema.py
index b718822..6702238 100644
--- a/sql_server/pyodbc/schema.py
+++ b/sql_server/pyodbc/schema.py
@@ -68,6 +68,7 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
     sql_rename_table = "EXEC sp_rename %(old_table)s, %(new_table)s"
     sql_create_unique_null = "CREATE UNIQUE INDEX %(name)s ON %(table)s(%(columns)s) " \
                              "WHERE %(columns)s IS NOT NULL"
+    sql_create_unique = "ALTER TABLE %(table)s ADD CONSTRAINT %(name)s UNIQUE (%(columns)s)"
 
     def _alter_column_default_sql(self, model, old_field, new_field, drop=False):
         """