new table or lots of null values

[shannonsider]

Hi,

I have a table of file information. For image files, I wish to include a
width and height field. Since most of my files are not images these fields
will be null in about 95% of records.

Is it better to put this field in a new table and create a join between the
two tables? Is having a field with a lot of null values wasteful? In Access,
unlike SQL Server, there is no varchar data type.

I would appreciate any advice.

Regards
John

 

[Allen Browne]

Just use 2 fields (since you want to store 2 things, i.e. width and height)
in your existing table. A related table with a one-to-one relation is not
really justified here.

You will want to use fields of type Number, since the values are numeric.

Numeric fields are fixed size, so your comment about a varchar doesn't
apply. However, the Text field in Access is actually variable width.

There is no way through the table-design interface to create a fixed width
text field (though it can be done programmatically if you really need to.)