Re: Encountered an error

On Thu, Mar 10, 2016 at 05:02:51AM -0800, Adrian Klaver wrote:

>>                 #First make the appropriate column

> This will not work for the reasons Daniele gave. You have two choices:
>
> 1) Build the SQL string using Python string formatting.
>
> 2) Do it with the Postgres format(). From a psql session:
>
> test=> select format('ALTER tbl_a ADD %I int DEFAULT NULL', 'fld_2');
>                  format
> ----------------------------------------
>  ALTER tbl_a ADD fld_2 int DEFAULT NULL
>
> In psycopg this is a two step process, submit the query and then resubmit
> the returned string.

While this is a nice solution to OPs problem I cannot resist
the urge to point out that to me the whole approach of adding
a column from within client code (outside a database
management application) does have at least a whiff of design
smell to it.

There's probably better ways to implement EAV. Approaches
with JSON, hstore, xml, or the venerable
CREATE TABLE inventory_detail(pk, fk_inventory, detail_name, detail_value)
come to mind.

Regards,
Karsten
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