The records in these tables include ID numbers of records from other tables.You can't learn much just by glancing at these records because the ID numbers don't tell you much about the data they relate to.
If you click on this Indexes button that will bring up a special view displaying all the indexes created for this table.
The last option Yes (No Duplicates) means that Access will automatically prohibit duplicate values in that field.
Let us now create an index for our last name field.
We now have two indexes for tbl Employees —one that was created automatically based on the primary key field and one that we just created for the Last Name field.
These are the different ways to deal with indexes in Microsoft Access tables.