Re: Update multiple rows in a table with different values

On Fri, Jul 1, 2016 at 10:26 AM, shankha <shankhabanerjee(at)gmail(dot)com> wrote:

>
> PREPARE updatearrayplan(BigInt[], BigInt[]) AS
> for i in size($1)
> DO
> update s.t1
> SET c3 = $2[$i]
> WHERE c2 = $1[$i]
> END FOR
>
> EXECUTE updatearrayplan({20, 30}, {275, 375})
>
> After execution of updatearrayplan I am expecting the rows to have
> these values 20 -> 275 , 30 -> 375
>
>
Have you looked at CREATE FUNCTION​?

I'd suggest the plpgsql language.

> Is there a way to update multiple rows with different column values
> passed in as array.

​No. All rows identified by a single where clause are updated using the
same expression. Though I suppose you could try something like:

c3 = CASE WHEN c2= 20 THEN 275 WHEN c2= 30 THEN 375​ END
WHERE c2IN (20, 30)

> Also is there a guarantee that the order of the
> arrays will be maintained.
>

That question is too broad. Direct iteration of an array will be done in
order. Whether, post-iteration, the resultant records remain in order is
not promised.

David J.