How to Insert Null Value in a Table

Hi

In my program i Filter the Book Issue Details with register number.

when i issue the Book i insert a Member Id in a field Called Mid and then select all those records with this Query

Select * from Books where Mid IS NOT NULL;

when the Books return i update the table with this Query

Update Books Set Mid ='"+" "+"' Where Bid ="+bid+";

Now in my program the Returned Books details are also Shown Why Because i update the Mid Field with " " Blank .

i think the SQL Query Consider this one as a Value

Please tell me how to overcome this

Thank you fro your service

Cheers

Jofin

[709 byte] By [jofin123a] at [2007-11-26 23:40:46]