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About relationships | 133
For example, a database for a travel agency might have these tables: a Tours
table, which stores the products (tours) and their current prices; a Clients table,
which stores client information; an Invoices table, which keeps a record of each
invoice; and a LineItems tables, which stores sales data for each line of the
invoice, including the tour being sold and the price at which it is sold. Because
invoices are a mix of dynamic and static data, you use both relational databases
and lookups to display your data. Records from the LineItems table are
displayed dynamically, in a portal on the Invoices layout, but the actual sales
price of each line item is entered using a lookup, so the invoice totals remain
historically accurate, even if prices change at some future date.
Lookups copy data from the related table into the current table
R20Client ID
NY-ParisRoute
R20Client ID
NY-ParisRoute
In relational databases, data from the related table is only
displayed in the current table, not copied
R20Client ID
NY-ParisRoute
R20Client ID
NY-ParisRoute
Current table Related table
Current table Related table
φμπ10_υσερσ_γυιδε.βοοκ Παγε 133 Μονδαψ, Αυγυστ 25, 2008 3:59 ΠΜ