PLPGSQL

On Mar 23, 2005, at 7:56 AM, Shaun Clements wrote:

Is there no way in pgplsql
to call on a dynamic column.
I need to be able to dynamically determine the latest month column
within a dataset, and to get that columns data.
I am unfamiliar with other languages within Postgres

Kind Regards,
Shaun Clements

You can get all the column names for a table called 'testtable' using:

select a.attname
from
pg_attribute a,
pg_class c
where
a.attrelid=c.oid and
a.attnum>0 and
c.relname='testtable';

You can then decide what column to use based on whatever logic you
like. You will then need to construct the SQL statement using ||
(concatenate) and execute it using EXECUTE.

http://www.postgresql.org/docs/current/static/plpgsql-
statements.html#PLPGSQL-STATEMENTS-EXECUTING-DYN

Does this help? Another simpler way to do this would be a different
table structure where you put the month in a column by itself rather
than a different column for each month.

Sean

On Mar 23, 2005, at 8:51 AM, Shaun Clements wrote:

Hi Sean

Ive chosen the table structure on purpose.
Im transforming data from one table to another. The problem is still
there.
I receive the column name from a query in one table, and then need to
update the table with that column name in another.

This needs to be done dynamically as part of a loop. So the column
name needs to be called as a variable.
Im stuck.

The answer is here to allow you to construct SQL statements from parts:

http://www.postgresql.org/docs/current/static/plpgsql-
statements.html#PLPGSQL-STATEMENTS-EXECUTING-DYN

You can pass your column name as an argument to a function that does
what you want and then concatenate it with whatever else you want in
your SQL. Then just EXECUTE the resulting statement.

Sean