diff --git a/tests/test_sql.py b/tests/test_sql.py
index 6fc1c6fce..e37ab6b42 100644
--- a/tests/test_sql.py
+++ b/tests/test_sql.py
@@ -128,12 +128,16 @@ def test_sql_get_missing():
     data_class = formdef.data_class(mode='sql')
     with pytest.raises(KeyError):
         data_class.get(123456)
+    with pytest.raises(KeyError):
+        data_class.get('xxx')
 
 
 @postgresql
 def test_sql_get_missing_ignore_errors():
     data_class = formdef.data_class(mode='sql')
     assert data_class.get(123456, ignore_errors=True) is None
+    assert data_class.get('xxx', ignore_errors=True) is None
+    assert data_class.get(None, ignore_errors=True) is None
 
 
 def check_sql_field(no, value):
diff --git a/wcs/sql.py b/wcs/sql.py
index 5286c30de..a722cc2a2 100644
--- a/wcs/sql.py
+++ b/wcs/sql.py
@@ -1021,6 +1021,7 @@ def do_global_views(conn, cur):
 
 class SqlMixin(object):
     _table_name = None
+    _numerical_id = True
 
     @classmethod
     @guard_postgres
@@ -1095,11 +1096,14 @@ class SqlMixin(object):
     @classmethod
     @guard_postgres
     def get(cls, id, ignore_errors=False, ignore_migration=False):
-        if id is None:
-            if ignore_errors:
-                return None
-            else:
-                raise KeyError()
+        if cls._numerical_id or id is None:
+            try:
+                int(id)
+            except (TypeError, ValueError):
+                if ignore_errors and id is None:
+                    return None
+                else:
+                    raise KeyError()
         conn, cur = get_connection_and_cursor()
 
         sql_statement = '''SELECT %s
@@ -1658,16 +1662,13 @@ class SqlDataMixin(SqlMixin):
     @classmethod
     @guard_postgres
     def get(cls, id, ignore_errors=False, ignore_migration=False):
-        if id is None:
+        try:
+            int(id)
+        except (TypeError, ValueError):
             if ignore_errors:
                 return None
             else:
                 raise KeyError()
-        else:
-            try:
-                int(id)
-            except ValueError:
-                raise KeyError()
         conn, cur = get_connection_and_cursor()
 
         fields = cls.get_data_fields()
@@ -1993,6 +1994,7 @@ class Session(SqlMixin, wcs.sessions.BasicSession):
         ('id', 'varchar'),
         ('session_data', 'bytea'),
     ]
+    _numerical_id = False
 
     @classmethod
     @guard_postgres
@@ -2084,6 +2086,7 @@ class TrackingCode(SqlMixin, wcs.tracking_code.TrackingCode):
         ('formdef_id', 'varchar'),
         ('formdata_id', 'varchar'),
     ]
+    _numerical_id = False
 
     id = None