User`s guide

the file name extension. For example, if you are using the dBASE database file Company.dbf, the
program will assign a default alias name of Company to the file. You can accept the default alias or
assign a new one to the database table.
You can change an alias at any time using the Database Expert. However, if you have already created
formulas in your report using the original alias name, you will need to edit the formulas to use the new
alias.
23.5 Linking tables
You link tables so records from one table will match related records from another. For example, if you
activate an Orders table and a Customers table, you link the tables so that each order (from the Orders
table) can be matched up with the customer (from the Customer table) that made the order.
When you link, you are using a field that is common to both tables. Crystal Reports uses the link to
match up records from one table with those from the other. In this example, the link assures that the
data in each row of the report refers to the same order.
23.5.1 Link from and link to
When you link two tables, you link from one table to another table. The from table is used as a primary
table, while the to table acts as a lookup table where records are looked up by the primary table. In a
simple link, the Report Designer examines the first record in the primary table and finds all matching
records in the lookup table. Once all matches have been found in the lookup table for the first record
in the primary table, all matches in the lookup table for the next record in the primary table are found.
23.5.2 Link relationships
When you link records from one table to another table, the records will typically fall under one of two
relationship types: one-to-one or one-to-many.
23.5.2.1 One-to-one relationships
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Understanding Databases