Re: Missing table from in INSERT RETURNING

[Rémi Cura <remi.cura@xxxxxxxxx>]

Hey folks,
thanks for the answers.
As you guessed it is just a synthetic example,

(so of course RETURNING some_value / 10  is possible in this case, but not in general when the function is much more complicated than "/10").

Same wise, adding a column is just not a serious option.

It correspond to a real need that is that you have rows associated to an id.

Now you want to insert part of this row into a table with a serial field (gid).

Upon insertion, the serial field is automatically filled, and you get it with a returning statement.
The problem is that you have no way to know which value of gid is associated to which id.

The other workaround I found is to get nextvalue() before insert to to know beforehand what will be the (gid, id)  association.

It is suboptimal and ugly, so I would prefer another solution.

Cheers,
Rémi-C

 

2015-02-17 21:33 GMT+01:00 John McKown <john.archie.mckown@xxxxxxxxx>:

On Tue, Feb 17, 2015 at 2:15 PM, David G Johnston <david.g.johnston@xxxxxxxxx> wrote:

On Tue, Feb 17, 2015 at 1:08 PM, John McKown [via PostgreSQL] <[hidden email]> wrote:

I haven't seen any one else reply. I don't know if you've gotten a solution. But the following seemed to work for me:

​mine apparently got bounced...​

 

WITH serie AS (

select s, s*10 as computing

from generate_series(1,10) as s 

)

INSERT INTO test_insert_returning (some_value)

SELECT computing

FROM serie

RETURNING gid, some_value;

​or, "RETURNING some_value / 10"​

From my reading on the RETURNING phrase, you can only return values from the table into which you are doing the INSERT. Not any other table or view which might be referenced.

​This is correct; and I am curious on the use case that requires otherwise.​

​A weird one might be where in data available ("s") in the CTE is in English measure (feet, miles, etc) and the OP wants to insert the equivalent Metric value ("computing") into the table, but needs to return the English value to the caller (why?). He does not want to put the English measure into the table itself, just to be able to return it. And not need to do a reverse conversion. As I said, just a weird thought. From a effervescent fount of weird thoughts - me. Or perhaps what he is storing in the table is a one-way hash of a password, and wants to return the clear-text password to the caller? Hum, that is almost reasonable. I'll need to be more on guard.

 

​David J.​

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John McKown