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Old 04-15-2019, 03:10 AM   #16
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Re: Help with database

Quote:
Originally Posted by mike60smart View Post
Hi



I tend to use Autonumber in every table.
I think some people would argue that you don't need an autonumber in something like say, a many to many table. However like you, I do tend to add an auto number field, particularly while developing, because it gives you some insight if something is going wrong.

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Old 04-15-2019, 06:46 AM   #17
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Re: Help with database

In a m-m table that has a child table, you do need an autonumber as PK to give you a single field PK for use in combos or listboxes but when the m-m table has no child tables, you can just use a compound PK comprised of the two FK's. For consistancy, I generally add an Autonumber as the PK even though it is redundant. The CRITICAL point is that you still MUST have a unique index on the two PKs or whatever makes the row unique. In some cases these m-m tables need even more columns for uniqueness. For example, if qualifications expire, there would be three parts to the unique ID - EmpID, JobID, ExpireID. That would allow the table to contain a new row for each expiration otherwise, you would need an additional child table if you needed to keep history of the certifications.

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