Subject: Re: New user questions
To: Rich Shepard <rshepard@appl-ecosys.com>, psycopg@postgresql.org
References: <alpine.LNX.2.20.2107131228540.11509@salmo.appl-ecosys.com>
 <36d964b4-e04b-5fdf-9b21-d3bf80a3505d@aklaver.com>
 <alpine.LNX.2.20.2107131457030.11509@salmo.appl-ecosys.com>
 <9b477722-71af-abbb-8db7-1390a9906b07@aklaver.com>
 <alpine.LNX.2.20.2107141029300.12992@salmo.appl-ecosys.com>
From: Adrian Klaver <adrian.klaver@aklaver.com>
Message-ID: <b030d87b-43d9-d994-7291-18a0caef0656@aklaver.com>
Date: Wed, 14 Jul 2021 10:57:47 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.7.0
MIME-Version: 1.0
In-Reply-To: <alpine.LNX.2.20.2107141029300.12992@salmo.appl-ecosys.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Archived-At: 
 <https://www.postgresql.org/message-id/b030d87b-43d9-d994-7291-18a0caef0656%40aklaver.com>
Precedence: bulk

On 7/14/21 10:35 AM, Rich Shepard wrote:
> On Tue, 13 Jul 2021, Adrian Klaver wrote:
> 
>> Then you want to take a look at this:
>> https://www.psycopg.org/docs/sql.html
> 
> Adrian,
> 
> Based on pages 1-2 of that doc I've re-written one each of an insert and
> select query. When they are correct I'll do the rest of the insert and
> select queries.
> 
> Query 1:
> cur.execute(
>      sql.SQL("insert into {} values (%s, %s, %s, %s, %s)"
>          .format(sql.identifier('contacts')),
>          [c.nbr, a.date, a.type, a.notes, a.next]))

Where are c.nbr and a.* coming from? If they are supposed to be table 
qualified values this will not work.

Also it is sql.Identifier.


> 
> Query 2:
> query = sql.SQL("select {fields} from {tables}").format(
>        fields = sql.SQL(',').join([
>        sql.identifier('p.lname'),
>        sql.identifier('p.fname'),
>        sql.identifier('p.loc_nbr'),
>        sql.identifier('p.job_title'),
>        sql.identifier('p.direct_phone'),
>        sql.identifier('p.active'),
>        sql.identifier('c.org_name'),
>        sql.identifier('l.loc_nbr'),
>        sql.identifier('l.loc_name'),
>        sql.identifier('a.act_date'),
>        sql.identifier('a.act_type'),
>        sql.identifier('a.notes'),
>        sql.identifier('a.next_contact'),
>        ])
>        tables = sql.SQL(',').join([
>        sql.identifier('people as p'),
>        sql.identifier('companies as c on c.org_nbr = p.org_nbr'),
>        sql.identifier('locations as l on l.org_nbr = o.org_nbr and 
> l.loc_nbr = p.loc_nbr'),
>        sql.identifier('contacts as a on a.person_nbr = p.person_nbr'),
>        ])
>        where p.lname = (%s) and p.fname = (%s)
>        group by a.act_date order by a.act_date", (lname,fname))


This will not work, if for no other reason that 'companies as c on 
c.org_nbr = p.org_nbr', etc are not identifiers and it is sql.Identifier.

Also it would be simpler for this case just to create a quoted 
statement, something like:
"""SELECT
    fld_1, fld_2, fld_3
FROM
    some_table AS st
JOIN
    another_table AS a
ON
     st.id = a.a_id
WHERE
     st.fld_1 = 'something'
"""
> 
>> For an UPDATE example see my answer to this Stack Overflow question:
>> https://stackoverflow.com/questions/68321746/how-to-create-a-dynamic-update-query-in-sql-using-python/68323019#comment120800261_68323019 
>>
> 
> I'll read this again in close detail after I understand how to write insert
> and select queries.
> 
> Regards,
> 
> Rich
> 
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com