On 2018-05-30 15:16:56 +0200, Félix GERZAGUET wrote: > On Wed, May 30, 2018 at 2:50 PM, PegoraroF10 <[email protected]> wrote: > So, is that possible to change a DO structure is ran, to be possible to > return one or more values ? > It would be like ... > DO returns(ID Integer, Description Text) as > $$ > begin > select ... > insert ... > select ... into ID, Description > end > $$ > > Using this way would be possible to create that script on client, call it > just one time and have a result for that execution, exactly the way a > "execute block" does on Firebird. [...] > > Since you seems to be able to construct dynamically the statement from the > client application, I think it is already possible to do that in one SQL > statement using CTE. [...] > So you can construct arbitrary complex thing using any combination of SELECT, > UPDATE and DELETE.
But note that:
| The sub-statements in WITH are executed concurrently with each other and
| with the main query. Therefore, when using data-modifying statements in
| WITH, the order in which the specified updates actually happen is
| unpredictable. All the statements are executed with the same snapshot
| (see Chapter 13), so they cannot “see” one another's effects on the
| target tables. This alleviates the effects of the unpredictability of
| the actual order of row updates, and means that RETURNING data is the
| only way to communicate changes between different WITH sub-statements
| and the main query.
--
https://www.postgresql.org/docs/10/static/queries-with.html#QUERIES-WITH-MODIFYING
In a DO block the statements are processed sequentially and each
statement sees the results of the previous statements.
hp
--
_ | Peter J. Holzer | we build much bigger, better disasters now
|_|_) | | because we have much more sophisticated
| | | [email protected] | management tools.
__/ | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
signature.asc
Description: PGP signature
