OID queries

[Bart Pietercil]

Hi Ruslan,


this is the part that I don't see how to resolve in SQL

    // Find table by its ID
     VTable tbl = this->get_Table( tblID );

For the rest I think we can use the bit functions, but I don't think  
we can use tblID directly in SQL ?
So we need something to convert from tblID to Tablename ?

thx

Bart
PS: just realizing the power of the OID field in combination with  
getTableID. Would change alot in the db design.

On 09 Jun 2008, at 11:02, Bart Pietercil wrote:

> Hi Ruslan,
>
> On 09 Jun 2008, at 10:02, Ruslan Zasukhin wrote:
>
>> On 6/9/08 10:45 AM, "Bart Pietercil" <bart.pietercil at cognosis.be>  
>> wrote:
>>
>> Hi Bart,
>>
>>> why does this query not work:
>>> select ** where OID = 176093659137
>>>
>>> gives unexpected token (wants to see FROM I guess)
>>
>> Right, should be
>>
>> SELECT **
>> FROM T
>> WHERE OID = 176093659137
>>
>>
>>> But since an OID is unique in the database and as I understand the
>>> first part of the ID refers to the table, shouldn't Valentina be  
>>> able
>>> to resolve this.
>>
>> Correction.
>>
>> VALUE of OID field is unique, right.
>>   but OID, like any other field, belongs to some table.
>>
>>
>>> I find this rather important since it spares me the addition of  
>>> adding
>>> a field to a table that identifies the table the id is coming from.
>>
>>> Just to make it clear I do not want to use an objectpointer  
>>> because an
>>> objectpointer is limited to pointing to a predefined table.
>>
>> Right, also note that
>>
>>   sizeof(ObjectPtr) == sizeof(ULONG)  == sizeof(ReCID) == 4
>>
>> But
>>   sizeof(OID) == 8
>>
>> So to have kind of POINTER ON OID, you need to use in some table  
>> ULLONG
>> field.
>>
>>
>>> In the design I need I need to be able to store a pointer to any
>>> table. Normally I solve this by using 2 fields (ID (long) and
>>> Tablename(varchar)).
>>> However this functionality seems to be in the OID but not  
>>> implement in
>>> the SQL parser.
>>
>>
>> I wonder, if you have see this page
>>
>> <http://www.valentina-db.com/dokuwiki/doku.php?id=paradigma:public:en:docume
>> ntation:vkernel:vfield:oid&s=oid>
>>
>> It give example of simple function which allow by OID value found  
>> table and
>> record.
>>
>> Let me know if this is not enough
>
> Well indeed this seems to point to the solution I am looking for  
> however I don't see how to translate this to SQL
>
> // This function returns a Table pointed by a given OID
> // and this Table has the current record pointed by OID.
> //
> VTable VDatabase.GoToRecord( inOID )
> {
>    TableID tblID = (TableID)(inOID >> 32);
>
>    // Find table by its ID
>    VTable tbl = this->get_Table( tblID );
>    if( tbl )
>        tbl.Recid = inOID & 0xFFFFFFFF;
>
>    return tbl;
> }
>
> Could I  write this as a stored procedure ?
>
> TIA
>
> Bart
> _______________________________________________
> Valentina mailing list
> Valentina at lists.macserve.net
> http://lists.macserve.net/mailman/listinfo/valentina