On Sat, Apr 17, 2010 at 12:10 AM, gretty <nill...@yahoo.com> wrote:
>
> Hello
>
> I am a programmer using SQLite3 to create a database for an application. I
> have been running into some problems with my SQL queries which I dont think
> are correct. Can you check them & correct them where relevant?
>
> Right now only one table exists, its layout is like so:
> [quote]
> Table = element
> 2 columns = property TEXT PRIMARY KEY, value TEXT
>
> ie, CREATE TABLE element(property TEXT PRIMARY KEY, value TEXT)[/quote]
>
> Are these queries correct?
>
> Check if property already exists in table:
> [code]
> SELECT property
> FROM element
> WHERE property == 'color';[/code]
>
The correct query would be
SELECT property FROM element WHERE property = 'color';
However, you already know the property = 'color', so why SELECT it?
> If I get NULL back that will mean that this property does not exist in the
> table? Is this correct?
>
Well, no. If you get no rows back then it means that property =
'color' doesn't exist. NULL would mean that the property does exist
but has no value.
> Change the value in a row where property equals color:
> [code]
> DELETE value
> FROM element
> WHERE property == 'color';
>
> INSERT INTO element(value)
> VALUE('orange')
> WHERE property == 'color';
>
What you really want is
UPDATE element SET value = 'orange' WHERE property = 'color';
I suggest you go through any of the many SQL tutorials you can find via Google.
> commit;[/code]
>
> Also I want to create a new TABLE with the name '#element' or '.element' but
> I always get an error because of the '#' & '.' characters. Is it possible to
> create a table with a '#' or '.' character in its name?
Yes. Quote the names with double quotes.
> --
> View this message in context:
> http://old.nabble.com/How-to-fix-Syntax---Check-exists-tp28274195p28274195.html
> Sent from the SQLite mailing list archive at Nabble.com.
>
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--
Puneet Kishor http://www.punkish.org
Carbon Model http://carbonmodel.org
Charter Member, Open Source Geospatial Foundation http://www.osgeo.org
Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor
Nelson Institute, UW-Madison http://www.nelson.wisc.edu
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