Re: Question about documentauion under Managers>Adding extra Manager methods

Unless I'm mistaken, it's PostgreSQL. The telling feature is the GROUP BY clause - PostgreSQL allows you to group by column index.

http://www.postgresql.org/docs/9.0/static/sql-select.html#SQL-GROUPBY

Since this is an eccentricity of PostgreSQL, it would be a good idea for us to modify that example in the docs, and use a more conventional GROUP BY statement that would be familiar to all SQL dialects. I've opened ticket #20168 to track this issue.

Yours,

Russ Magee %-)

On Sun, Mar 31, 2013 at 5:49 AM, James Durham <jamesldurham@gmail.com> wrote:

In this instance, what I'm asking is about the documentation.
In other words does anyone recognize the dialect.
It would just help in understanding docs.
Though, thanks for indicating that it is backend dependent.

On Friday, March 29, 2013 8:40:09 PM UTC-5, Russell Keith-Magee wrote:

On Sat, Mar 30, 2013 at 6:20 AM, James Durham <jamesl...@gmail.com> wrote:

In the example:

class PollManager(models.Manager):      def with_counts(self):          from django.db import connection          cursor = connection.cursor()          cursor.execute("""              SELECT p.id, p.question, p.poll_date, COUNT(*)              FROM polls_opinionpoll p, polls_response r              WHERE p.id = r.poll_id              GROUP BY 1, 2, 3              ORDER BY 3 DESC""")          result_list = []          for row in cursor.fetchall():              p = self.model(id=row[0], question=row[1], poll_date=row[2])              p.num_responses = row[3]              result_list.append(p)          return result_list    class OpinionPoll(models.Model):      question = models.CharField(max_length=200)      poll_date = models.DateField()      objects = PollManager()    class Response(models.Model):      poll = models.ForeignKey(OpinionPoll)      person_name = models.CharField(max_length=50)      response = models.TextField()

What is the sql dialect that is used.

In this case you're opening a cursor, so you use whatever dialect your database uses. If you're using PostgreSQL, use PostgreSQL syntax; if you're using MySQL, use MySQL syntax. 

Django's ORM hides syntax differences from you; but once you start dealing with database cursors or raw() queries, you're coding right to the metal, so your deployment environment matters.

Yours,

Russ Magee %-)

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