Joined: 13 Feb 2004 Posts: 360 Location: Bangalore
Lets say we create a table
CREATE TABLE EMP (EMPID INT CHECK (EMPID > 1000) NOT ENFORCED
ENABLE QUERY OPTIMIZATION)
here the check constraint is an informational one ..its used to increase performance ...now if u insert a row with empid = 100 the insert will be successful but if u say SELECT * FROM EMP WHERE EMPID = 90 this will return none as u have already set an access path where empid > 1000 ...
its just like telling the optimizer that empid will always be greater than 1000 so dont chk for anything less than that ...
