diff options
Diffstat (limited to 'docs/ref')
| -rw-r--r-- | docs/ref/models/querysets.txt | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt index 2da85600f7..2db252d006 100644 --- a/docs/ref/models/querysets.txt +++ b/docs/ref/models/querysets.txt @@ -379,17 +379,14 @@ query spans multiple tables, it's possible to get duplicate results when a :meth:`values()` together, be careful when ordering by fields not in the :meth:`values()` call. -You can pass positional arguments (``*fields``) in order to specify the names -of fields to which the ``DISTINCT`` should apply. This translates to a -``SELECT DISTINCT ON`` SQL query. Here's the difference. For a normal -``distinct()`` call, the database compares *each* field in each row when +On PostgreSQL only, you can pass positional arguments (``*fields``) in order to +specify the names of fields to which the ``DISTINCT`` should apply. This +translates to a ``SELECT DISTINCT ON`` SQL query. Here's the difference. For a +normal ``distinct()`` call, the database compares *each* field in each row when determining which rows are distinct. For a ``distinct()`` call with specified field names, the database will only compare the specified field names. .. note:: - This ability to specify field names is only available in PostgreSQL. - -.. note:: When you specify field names, you *must* provide an ``order_by()`` in the QuerySet, and the fields in ``order_by()`` must start with the fields in ``distinct()``, in the same order. @@ -398,7 +395,7 @@ field names, the database will only compare the specified field names. value in column ``a``. If you don't specify an order, you'll get some arbitrary row. -Examples:: +Examples (those after the first will only work on PostgreSQL):: >>> Author.objects.distinct() [...] |