Re: Inject rows into query resultes

On Tue, Sep 22, 2015 at 6:22 PM, Alex Magnum <magnum11200(at)gmail(dot)com> wrote:

> Hi,
> I am having a problem where I need to inject rows into a query result.
> That is
>
> I have a list of add records, lets say car listings which I select from a
> table. The order of the results are given either by the user or
> default/initial.
>
> I now want to inject featured car adds after every 5th record. (coming
> from the same table)
>
> Right now, I am doing this on the PHP just calling the query twice but I
> am wondering if there is a way to only run one query.
>

​I have no clue how you expect to "run one query" AND "so the original
listing should not be affected". ​

> The main problem is that
> a) i am using paging so the original listing should not be affected​​
>
b) the injected records should not be in the results returned for the
> current page.
>

​I have no clue what these mean since if you don't intend to show them why
retrieve the feature car ads (one d) in the first place?
​

>
> Any one having an idea how to solve that?
>
>
​Solving the ordering problem has a simplistic brute-force algorithm (you
may need to fix off-by-one errors in the logic - but the idea holds)

SELECT *, (((row_number-1) / 5) * 10​) + ((row_number-1)) % 5) AS
"rows_0_to_4_in_the_current_decade"
UNION ALL
SELECT *, ((row_number - 1) * 10) + (5) AS "row_5_in_the_current_decade"

Now you have: [0-5] [10-15] [​20-25], etc... as your "row index" where
every "5" record is your injected row.

Hopefully this helps - you have provided insufficient and/or contradictory
information regarding your actual problem.

David J.