magic-removal: Fixed #1082 -- Added a 'supports_constraints' variable for each database backend, and set SQLite's to False

git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@1757 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management.py

@@ -117,6 +117,7 @@ def get_sql_create(app):
 
         # Take care of any ALTER TABLE statements to add constraints
         # after the fact.
+        if backend.supports_constraints:
             if klass in pending_references:
                 for rel_class, f in pending_references[klass]:
                     rel_opts = rel_class._meta

django/db/backends/ado_mssql/base.py

@@ -76,6 +76,8 @@ class DatabaseWrapper:
             self.connection.close()
             self.connection = None
 
+supports_constraints = True
+
 def quote_name(name):
     if name.startswith('[') and name.endswith(']'):
         return name # Quoting once is enough.

django/db/backends/mysql/base.py

@@ -83,6 +83,8 @@ class DatabaseWrapper:
             self.connection.close()
             self.connection = None
 
+supports_constraints = True
+
 def quote_name(name):
     if name.startswith("`") and name.endswith("`"):
         return name # Quoting once is enough.

django/db/backends/postgresql/base.py

@@ -49,6 +49,8 @@ class DatabaseWrapper:
             self.connection.close()
             self.connection = None
 
+supports_constraints = True
+
 def quote_name(name):
     if name.startswith('"') and name.endswith('"'):
         return name # Quoting once is enough.

django/db/backends/sqlite3/base.py

@@ -70,6 +70,8 @@ class SQLiteCursorWrapper(Database.Cursor):
         # XXX this seems too simple to be correct... is this right?
         return query % tuple("?" * num_params)
 
+supports_constraints = False
+
 def quote_name(name):
     if name.startswith('"') and name.endswith('"'):
         return name # Quoting once is enough.