Re: [SQL] Update problem I cannot work out - Mailing list pgsql-sql

>
>     Try something like:
>
>     Create function new_function(value_data_type)
>         'Select sum(t1.var1) from t1 where t1.var2 = $1'  LANGUAGE
> 'sql';
>
>     update t2 set var1=t2.var1+new_function(t2.var2);
>

*snip*

Hi, thanks for replying.

My reply to this is the question, that as each function contains a
select, is this technically a single pass.

I get the feeling there will be tremendous overhead on this theory with a
large dataset, in comparison to a single query that does the
update. Can anyone comment on how much slower this could be (although
obviously if there is no way to do it in a single query then there is
no choice)?

Thanks

                        M Simms