If data has integrity, the data is valid—correct and accurate—and the relational structure of the database is intact. Referential integrity constraints enforce the relational structure of the database. These rules maintain the consistency of data between tables. Building integrity constraints right into the database is the best way to make sure your data stays in good shape.
You can enforce several types of integrity constraints. For example, you can ensure individual entries are correct by imposing constraints and CHECK constraints on tables and columns. You can also configure column properties by choosing an appropriate data type or setting special default values.
SQL Anywhere supports stored procedures, which give you detailed control over how data enters the database. You can also create triggers, or customized stored procedures that are invoked automatically when a certain action, such as an update of a particular column, occurs.
For more information about procedures and triggers see Using Procedures, Triggers, and Batches.
How data can become invalid
Integrity constraints belong in the database
How database contents change
Data integrity tools
SQL statements for implementing integrity constraints