Rossitza Kanovska

• Aug 9th, 2005

 

An integrity constraint is a rule that restricts the values in a database. There are six types: 
A NOT NULL constraint prohibits a database value from being null.  
A unique constraint prohibits multiple rows from having the same value in the same column or combination of columns but allows some values to be null.  
A primary key constraint combines a NOT NULL constraint and a unique constraint in a single declaration. That is, it prohibits multiple rows from having the same value in the same column or combination of columns and prohibits values from being null.  
A foreign key constraint requires values in one table to match values in another table.  
A check constraint requires a value in the database to comply with a specified condition.  
A REF column by definition references an object in another object type or in a relational table. A REF constraint lets you further describe the relationship between the REF column and the object it references.  

Shivani Goel

 Profile Answers by Shivani Goel Questions by Shivani Goel

• Jun 23rd, 2009

 

Integrity constraint is that which depend upon the parent and child relationship
in which parent column have the primary constraint and child column have the foreign
key constraint.
You cannot delete the any value from column that have foreign key constraint until
you never delete its related primary key column value, that is a integrity constraint.

If you try to do this it will show you error related to integrity constraint.