[ic] How can I nest loops or queries?

Dan B db@cyclonehq.dnsalias.net
Mon, 26 Feb 2001 18:50:24 -0800

At 05:59 PM 2/25/2001 +0000, chaim klar wrote:
>How can I nest loops or queries?

Does this help?

Taken from recent post by Mike Heins:


Quoting Dan B (db@cyclonehq.dnsalias.net):
 > Solved it, works perfect.  :-)  Thanks to Christopher F. Miller and the
 > mailing list archive.  Hopefully this will come in handy to the next person
 > searching the archives.

And though I jumped in late, there actually isn't any reason you can't nest a
query. I don't know why I never remembered to remove the "canNest" check for
Tagref.pm, but that is actually a legacy from the less-capable MV3 parser.

This nested query:

     [query list=1 prefix=outer sql="select category from products"]
                 list=1 prefix=inner
                     SELECT sku,description
                     FROM products
                     WHERE category = '[outer-code]'
                 "][outer-code] : [inner-code] : [inner-param description]<BR>

seems to work fine. Of course you have to have separate prefix= things
so the placeholders get substituted correctly, but it will work. As will
a loop in a loop, etc. Not the best way to get great performance, though. 8-)

Red Hat, Inc., 131 Willow Lane, Floor 2, Oxford, OH  45056
phone +1.513.523.7621 fax 7501 <mheins@redhat.com>

Experience is what allows you to recognize a mistake the second
time you make it. -- unknown

>I have two tables  the first table called products looks like this:
>p_sku   price   ...,
>C2100Z  14.50
>C211Z   45.35
>KF800   63.98
>KW      51.21
>KFP     45.92
>KFW     51.62
>...     ....
>Then another table called accessories that looks like this:
>AutoNumber      a_code  accessory
>1       KF800   C2100Z
>2       KF800   C211Z
>3       KF800   KW
>4       KF800   KFP
>5       KF800   KFW
>6       C2100Z  MBSM
>7       C2100Z  16MBSM
>8       C2100Z  32MBSM
>9       C2100Z  64MBSM
>10      C2100Z  B28
>(a_code may exist a few for each item in the products table)
>So in the flypage.html I first look up in the accessories table with the 
>item to see if it has  accessories (and to convince myself that it indeed have
>accessories for the current item I first display them) and then with the 
>I make another loop in the products table to get the price and description 
>for the
>accessories like this:
>[loop prefix=outer 
>         [outer-data accessories a_code][outer-data accessories accessory]
>         [loop prefix=inner search="fi=products/se[outer-data accessories 
> accessory]/co=yes/sf=p_sku/st=db"]
>                 [inner-data products p_sku][inner-data products price]
>         [/loop]
>but for some reason I get the accessories to display before entering the 
>second loop but not
>after the second loop so I have tired doing it with [query] like this:
>            st=db
>            list=1
>            sql=|
>                            SELECT p_sku
>                            FROM products
>                            WHERE p_sku IN (
>                                            SELECT accessory
>                                            FROM accessories
>                                            WHERE a_code = 'KF800'
>                                            )
>                |
>    [sql-increment]) [sql-param p_sku]<br>
>but I didn't get better results.
>Thanking You in advance.
>Chaim Klar
>Get your FREE download of MSN Explorer at http://explorer.msn.com
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Dan Browning, Cyclone Computer Systems, danb@cyclonecomputers.com