field size

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3 total messages Started by Ed Thu, 10 Jan 2008 02:33

#141

Author: Ed
Date: Thu, 10 Jan 2008 02:33

24 lines
1465 bytes

Hi,

I understand that TTable.items[x].size contains the size of
the field; but this depends entirely on what the DataType is.

Is there a way to find out the actual 'length' of the field?

If the table itself has the following definition:

MyTable.db:

fldname     character   20
fldindex    numeric     10  0
fldate      date         0  0
flblob      memo         0

How does one go about in finding the above?

For datatype = float,  the precision and size = 0.
For datetypes          the precision and size = 0

Any help appreciated

Edmund

Re: field size

#142

Author: Zoren Lendry
Date: Thu, 10 Jan 2008 03:00

25 lines
2274 bytes

Ed wrote:
> Is there a way to find out the actual 'length' of the field?
> How does one go about in finding the above?
> For datatype = float,  the precision and size = 0.
> For datetypes          the precision and size = 0

Are you asking about how much space a given data type takes in the 
underlying db? If so, then it depends on the database you are using. For 
instance, InterBase and Firebird have 3 separate datatypes for dates and 
times: Timestamp, which occupies 8 bytes, has both a date and a time 
portion. The Date portion is the Integer part, and the Time portion is 
the Float (fraction) part. A Date by itself takes 4 bytes, and contains 
no time information. A Time by itself takes 4 bytes, and contains no 
date information. A Double probably takes 8 bytes. A Boolean takes 2 
bytes. Numeric/Decimal up to a precision of 9 occupies 4 bytes, 8 bytes 
beyond 9.

As far as the TField descendants are concerned, you will get size and 
precision of 0 where the values are irrelevant. For instance, for an 
exact numeric type (NUMERIC/DECIMAL in IB/FB), the precision and scale 
matter a great deal. But for a Double? It just is what it is, up to the max.

You need to say what DB you're using, because it makes a difference.

Loren sZendre

Re: field size

#179

Author: Ed
Date: Fri, 11 Apr 2008 09:56

15 lines
1463 bytes

Zoren Lendry wrote:
> 
> As far as the TField descendants are concerned, you will get size and 
> precision of 0 where the values are irrelevant. For instance, for an 
> exact numeric type (NUMERIC/DECIMAL in IB/FB), the precision and scale 
> matter a great deal. But for a Double? It just is what it is, up to the 
> max.
> 
> You need to say what DB you're using, because it makes a difference.
> 
Hi Zoren,

I'm talking about tables from a FoxPro Database.

Edmund

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