Working with related tables > About relationship criteria
About relationship criteria
When you join two tables using a relationship, you establish criteria that FileMaker Pro uses to display or access related records.
Your criteria can be simple, such as matching a field in TableA with a field in TableB with equal values. A more complex relationship definition usually returns a narrower set of related records. Examples of complex relationships include using multiple match fields on one or both sides of the relationship, comparing match fields using non-equal relational operators, or using calculated match fields.
The following table describes the types of criteria you can use when creating relationships.
Relationship type
Relates two tables based on a single common value, such as a serial number or an ID number. See Single-criteria relationships.
Relates two tables based on more than one common value, such as a customer ID and a date. See Multicriteria relationships.
Comparative criteria
Uses one or more relational operators to compare match field values in two related tables. See Relationships that use comparative operators.
Range of records
Similar to a multicriteria relationship, it uses comparative operators to find a range of records that are greater than one criteria and less than the other criteria. See Relationships that return a range of records.
Related topics 
Planning a relational database
Working with the relationships graph
Creating and changing relationships