A primary key is graphically marked by a yellow key icon in Toad Data Modeler.įoreign key: A foreign key is a key that references a primary key or a unique key in another table. A primary key cannot contain null values. A table can have only one primary key, which can consist of one or more attributes. Primary key: A primary key is a key that uniquely identifies each record in a table. Toad Data Modeler supports the following types of keys: What types of keys does Toad Data Modeler support?
Keys can also be used to improve the performance of queries by creating indexes on key columns. Keys can be used to enforce data constraints, such as preventing duplicate or null values, and to link tables together through foreign key references. Keys are attributes or combinations of attributes that uniquely identify or reference records in a table.