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Chapter 4
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Working with related tables and files 101
Relationships using comparative operators
In a comparative relationship, you use one or more of the following operators to compare match field values
in the two related tables. The relationship returns related records when the comparison evaluates
successfully, according to the criteria you establish.
In this example, the Tour Date fields in the Tours table and the Clients table are match fields. If a record in
the Tours table has a Tour Date value of 12/11/2010, all the records in the Clients table with a Tour Date
value of 12/10/2010 or earlier are related to it. In the Clients table, if a record has a Tour Date value of
12/11/2010, all records in the Tours table with Tour Date values of 12/12/2010 or later are related to it.
Relationships that return a range of records
A relationship that returns a range of records is similar to a multi-criteria relationship, except that you use
comparative operators to find records that are greater than one of your criteria and less than your other criteria.
This type of relationship is commonly used to return records that fall between a range of dates or serial numbers.
For example, from within Table E you want to view all the records in Table F that have Date Field F values
that are greater than Starting Date E values and less than Ending Date E.
This relationship returns those records from Table F that have a Date Field F value that is later than Starting Date E
and earlier than Ending Date E.
Relational operator Matches these records
= Values in match fields are equal
Values in match fields are unequal
< Values in the left match field are less than values in the right match field
Values in the left match field are less than or equal to values in the right match field
> Values in the left match field are greater than values in the right match field
Values in the left match field are greater than or equal to values in the right match field
x
All records in the left table are matched to all records in the right table, regardless of the values in the match fields
Greater than relational operator
Match field Match field
Indicates that several different
relational operators are used in
this relationship
Match fields
Match field
This relationship uses the
greater than and less than
relational operators