This is a design question really so here are my recomendations.
Persons
- ID ( an integer primary key )
- Name
- Birthday
- Picture Type ( your two digit type).
Picture
- ID (An integer Primary Key that matches the ID of persons).
- image (blob)
Thus if you alread have the Persons record, you can get the picture as a
simple select on the Picture.image field by
select image from Picture where id = ?
Stef Mientki <[EMAIL PROTECTED]> wrote:
Cesar Rodas wrote:
> Save into a blob.
>
thanks but that's not what I meant.
I'll try to explain with an example:
I want to create this database
Persons
- Name
- Birthday
- Picture
Now when I want to view this database with a general database browser /
manager,
I'll first find out what tables there are in this database,
Secondly I'm going to ask for an overview of each table by, that will be
displayed in a flat table (2-dimensional matrix)
SELECT * FROM Persons
Now the browser sees the blob field at displays is something like "{blob}"
So I assume, that the browser get's all the data, including all the bits
and bytes of each image in each record,
so a whole lot of not-needed data, because the database browser /
manager can con display 1 picture from a selected record.
So I think, it would be more efficient to create 2 tables:
Persons
- Name
- Birthday
- ID ("this is a picture")
Blobs
- Name
- Picture
Now if I ask for the main table "Persons", I just get an ID (some
integer), that tells me that there is a picture.
The browser / manager can ask for just one record from the table Blobs,
to show me the picture of the selected line.
I've never seen such a construct in examples, so maybe I see ghosts
where there are none.
forgive me my ignorance.
cheers,
Stef Mientki
> here is a C example http://www.sqlite.org/cvstrac/wiki?p=BlobExample
>
> On 23/02/07, Stef Mientki wrote:
>> hello,
>>
>> I've started with SQLite, because it's one of the first dbases with a
>> local filessytem without authenciation.
>> It looks great, compared to ini-files.
>>
>> Now I've a basic problem:
>> I've a table, with 10 simple fields and 1 blob field, containing a
>> (possibly large) image.
>> Uptill now the dbase is small so no performance problems yet.
>> But what if it grows ?
>>
>> I want to look at the table in a table overview,
>> where the blob-field just displays the type of image
>> (identified by the fisrt 2 bytes SOI-code).
>>
>> When I ask for the table through a query,
>> I get all the blob-filed information, while I only need the first 2
>> bytes,
>> and only the full picture of 1 selected record.
>>
>> I can think of several solutions, but as my experience with databases is
>> almost zero, I can't decide
>> (and maybe I'm overlooking some better solutions)
>> solution 1:
>> add a extra field for each blob field, filled with the first 2 bytes of
>> a blob
>> solution 2:
>> put the blob fields in a separate table, with a link to the main table
>>
>> any suggestions would be appreciated.
>> thanks,
>> Stef Mientki
>>
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