In 4D it is possible to create composite primary keys.

There are a couple ways to perform this.

Method 1: Structure Editor

1. First highlight the Fields that will be part of set of composite primary keys.
   Note: Press and hold the control key to select multiple non-adjacent fields
2. Contextually click a highlighted record
3. Select Create Primary Key

This will create composite primary keys.

Method 2: By Code Using SQL Statements

To create composite primary keys using SQL statements, list the fields in the parenthesis as if creating a typical primary key.

For example:

Begin SQL    ....    CONSTRAINT {ConstraintName} PRIMARY KEY({Field1}, {Field2}, ... {FieldN})    .... End SQL

Also note that when using composite primary keys they will need a composite index containing the same fields or there will be an indexing error.

Tech Tip: Creating Composite Indexes