Ms access update set null

If a multiple-field constraint is designated as a unique key, the combined values of all fields in the index must be unique, even if two or more records have the same value in just one of the fields.

All values in the primary key must be unique and not Null , and there can be only one primary key for a table. If the foreign table's primary key consists of more than one field, you must use a multiple-field constraint definition, listing all of the referencing fields, the name of the foreign table, and the names of the referenced fields in the foreign table in the same order that the referencing fields are listed.

If the referenced field or fields are the foreign table's primary key, you do not have to specify the referenced fields. By default the database engine behaves as if the foreign table's primary key is the referenced fields. Foreign key constraints define specific actions to be performed when a corresponding primary key value is changed:.

For example, consider the following definition for the table Customers:. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Please rate your experience Yes No. Will this approach only update those fields in the record that are null. In all honesty, you really don't need anything in the criteria simply because the IIf takes care of it Run again Could get tiresome if you have to do it more than once Hi datAdrenaline, That is awesome. Thanks so much for your help on this one.

May have taken a while to get there but will save a lot of time in other situations now that I understand what is happening.

Thanks for everyone's help on this also, Cheers Ian. You must log in or register to reply here. Similar threads C. Get Minimum value except for 0 zero. Replies 3 Views Aug 18, theDBguy. Replies 7 Views Jul 29, Minty. Replace Null Values with Zeros. Drand Apr 1, Forms. I don't allow empty strings in tables but if you want: Nz rst!

FirstName, "". Add a comment. Active Oldest Votes. Value If the field that you are updating is numeric then you'll need to return a Zero value if null: Nz rst. Improve this answer. So I guess the IsNull function isn't needed. Don't you mean the IsNull function is needed? IIf varFreight, 0, varFreight would return 0 if varFreight evaluated to True and would return varFreight if varFreight evaluated to False which it will do if it is Null.

Argh - too early in the morning to be thinking of logical variables! You would use Null without the quotation marks e. Show 2 more comments. Gustav Gustav 47k 6 6 gold badges 29 29 silver badges 52 52 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook.