Enforcing Data Integrity

Planning and creating tables requires identifying valid values for the columns and deciding how to enforce the integrity of the data in the columns. SQL Server 2005 provides the following mechanisms to enforce the integrity of the data in a column:

• PRIMARY KEY Constraints
  
• FOREIGN KEY Constraints
  
• UNIQUE Constraints
  
• CHECK Constraints
  
• DEFAULT Definitions
  
• Allowing Null Values