Difference btwn field lookup and setting relationship

  • Thread starter Thread starter Aaron
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A

Aaron

I'm building my first relational database, and I'm unsure about something...

When defining a field using lookup, I am able to choose what table I am
allowed to choose from (primary keys only, it seems). If I update that
other table, this shows up in the lookup. Now, the thing I don't
understand is, what is the difference between this example and setting a
relationship between two fields from two different tables? The same
effect seems to apply here too...update one field and it affects the
other.

Could someone explain this to me?

Thanks,
Aaron
 
I'm building my first relational database, and I'm unsure about something...

When defining a field using lookup, I am able to choose what table I am
allowed to choose from (primary keys only, it seems). If I update that
other table, this shows up in the lookup. Now, the thing I don't
understand is, what is the difference between this example and setting a
relationship between two fields from two different tables? The same
effect seems to apply here too...update one field and it affects the
other.
Click to expand...

Microsoft's "Lookup" feature is (among other things) one of a couple
of ways by which one can create a relationship between tables. In fact
it will create a new (redundant) relationship even if you've already
created a relationship in the Relationships window, or in
table-creation SQL code.

The Lookup feature is not well regarded by may developers: among other
things it conceals the actual contents of your table, and it
encourages use of table datasheets for routine data entry and
presentation. Forms (with combo boxes, "lookups" if you will) are
better suited for this purpose.

See http://www.mvps.org/access/lookupfields.htm for a critique.
 
Hi Aaron,

I won't go into lengthy explanations nor comparisons because you should
NEVER use the Lookup Field type in your table designs! They will lead you
into trouble as you keep building and enhancing your applications. For your
own edification you might do a Google search on Lookup Fields and see what
people have had to say.

As to relationships, there are several different kinds. Each one has a
purpose that's different from any other.

HTH
 
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