Search Postgresql Archives

Re: Interesting abilities of substring

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Sure, we use a user interface widget called "Ajax Dynamic List" from www.dhtmlgoodies.com. This replaces the HTML SELECT element.

When a user is sitting on a foreign-key field, such as a PATIENT or CUSTOMER field, the user can just start typing letters or numbers. An AJAX call is made to the back end which searches all columns in a pre-defined list. If the list is first_name,last_name,dob, and they type "ken" they will get everybody whose first name or last name begins with 'ken', and the date is ignored. If they type '1991' they will get everybody born in 1991, and of course '1991-10' returns everybody born in October 1991.

So it turns out that both string concatenation and substring do some nifty implicit typing. This means making the generalized lookup requires you only to know the list of columns, without also needing to know their types.

SELECT patient as _value
     ,patient
       || ' - ' || namlst
       || ' - ' || nam1st
       || ' - ' || phone
       || ' - ' || ssn
|| ' - ' || dob as _display FROM patients WHERE ( SUBSTRING(LOWER(patient) FROM 1 FOR 2)='ke'
      OR SUBSTRING(LOWER(namlst) FROM 1 FOR 2)='ke'
      OR SUBSTRING(LOWER(nam1st) FROM 1 FOR 2)='ke'
      OR SUBSTRING(LOWER(phone) FROM 1 FOR 2)='ke'
      OR SUBSTRING(LOWER(ssn) FROM 1 FOR 2)='ke'
OR SUBSTRING(LOWER(dob) FROM 1 FOR 2)='ke') ORDER BY patient Limit 20

Eventually I will be driven to optimize that, but on tables < 10,000 rows it is still well within the threshhold of the human attention span of < .5 second or so.

Naz Gassiep wrote:
This may be useful to me and others, care to paste an example of what you mean?
Thanks,
- Naz.

Kenneth Downs wrote:
Here is something cool that I did not realize postgres's substring() could do.

Basically, it "knows what you mean" when you do substrings on dates and numbers, doing an implicit cast for you. This is really nice if you happen to be writing a generalized search system, as it makes the code significantly simpler...

That's all, now back to our regularly scheduled mailing list.



--
Kenneth Downs
Secure Data Software, Inc.
www.secdat.com    www.andromeda-project.org
631-689-7200   Fax: 631-689-0527
cell: 631-379-0010


---------------------------(end of broadcast)---------------------------
TIP 5: don't forget to increase your free space map settings

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux