Null Value

[wg26]

Hi Everyone:

Can anyone please tell me if Null value in the column will take up the whole bytes, which the column data type will allocate. Say I have a column which has data type float (8 bytes),if this column is Null, does SQL allocate 8 bytes to hold this Null value,or does it just allocate smaller bytes? Thanks alot.

 

[LFCfan]

A consultant told me once that NULL will take no bytes at all in numeric/float fields. Basically he said that if there's a zero instead of a NULL in a number-type field, the field for that record will take up all the bytes that the data type dictates (eg 4 bytes for an INT data type). If there's a NULL the overall byte length of that row will be smaller.

If I remember correctly, this doesn't apply to CHAR data types - ie a CHAR(8) entry will take up 8 bytes whether it contains a NULL or not.

Take what I say with a pinch of salt though, as I could be wrong!

Hope it helps

Maria

 

[wg26]

Thank you very much Maria.

I have created a table and tested it...It seems to me that Null value does take some bytes. I don't know if it takes whole bytes though...but it is true that overall byte length of the row is smaller with Null value than with a default value of whatever the data type is...

Once again, thank you for your kindly reply...