What does each record in this table represent? (Why would you have two records with the same manufacter?)
How will you use this list?
There are several approaches that work, but a bigger picture will help identify the best one to use.
When users create new record, they will enter manufacturers.
I want to evade this kind of duplicate entry
I understand that to mean that you don't want the duplicate record created in the first place.
If so, you can open manage | Database | fields and double click the manufacturers field. Then click the validation tab in the field option dialog that appears and specify the "unique values" validation. This way, entering the name of an existing manufacturer in a new record will produce an error message when this unique values validation rule is violated.
Thanks you very much for answering. But my problem is :
etc. Users will enter many products. So, When they enter the product, they will need to fill manufacturers. So, sometimes, manufacturer can be entered multiple times. When I list the list of manufacturers, the list will show manufacturers from every records. If there are 2 records consist of 2 different products and 1 same manufacturer. The list will show 2 same manufacturers. how can I solve this? Does we have another ways to do these?
I suggest that you create related table of manufacturers. Your users would select from a drop down list of manufacturers or click a button to perform a script that creates a new manufacturer record when needed.
To get a list of manufacturers without duplication, you list the records in the manufacturers table.
Really thanks for the answers. You've given a nice idea. Really thanks. :)