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#1
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Look up tables vs. relationships design
In my pond database, I have look up tables which merely contain a field for
an ID (primary key, autonumber) and a field for a category (e.g., "0-25%", "26-50%", etc., or "Dry", "Rainy", "Snowy"). These look up tables serve merely to populate selection options for combo boxes in my data entry forms and one look up table can be used multiple times (for multiple fields) on the same form. Do these IDs need to be linked with foreign keys in the data tables in the Relationships window? What determines what needs to be defined in Relationships (e.g., if you want to enforce referential integrity)? Or is the thinking that you should always link any table in Relationships? Jill |
#2
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Look up tables vs. relationships design
I noticed that nobody answered yet. Here's my two cents, maybe to trigger
other responding. If you are using a table as a list to populate a dropdown/combo box to populate a field, I see no need to define a link. In fact, even though it's a table, and, if you use in-table look-up fields (as the developers never do ) those links can show in the relationships window, I would consider drop-down lists to be a fundamentally different situation from linking tables with stored information. In the latter case, each of the linked records is databased information about the entity which is the record, and the linkage documents a relationship between those two records. Incidentally, the latter "linkage" is a three step process rather than just drawing a line: - Create the FK field - Put the PK value of one record into the FK field of the other. In my view, this is the main linking process - draw the line in the relationships window,create the line in an SQL statement etc. Something you already know, but a different way of saying.... If you have a data rule which Access "referential integrity" will enforce and you want it to do so, then you'll need to defin it in the relationships window. |
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