how do I combine two columns to create a third column

[Guest]

I am trying to combine data from two columns to create a unique ID that
populates a third column.

Ex. Auto number field + Company Name = LocationID

 

[Rick B]

You would not populate a new column. If you want a compound key for your
table, just click VIEW and INDEXES while you are in design view.

You can then create an index name and select the first field.
On the next line, leave the name blank and select your next field.
Then set the Unique property.

This will create a compound index.

Rick B

 

[Duane Hookom]

Generally a bad idea to store a value that can be derived. Do you have a
solid reason to save the combined value?