The point what I want to share with you is in DB2 certification what kind of questions you need to put more focus. These are DB2 constraints.
According to IBM, A constraint is a rule that is used for optimization purposes
There are many constraints in DB2. NOT NULL constraints, default constraints, CHECK constraints, UNIQUE constraints, and referential integrity constraints.
I don’t have to be smarter than anybody else. I’ve just plain worked harder and longer than anybody else. Graham Hawkes
NOT NULL constraint– constraint is a rule that prevents null values from being entered into one or more columns within a table
Default constants-DEFAULT constraint provides a default value to a column
Check Constraints-sets restrictions on data added to a specific table. For example, a table check constraint can ensure that the salary level for an employee is at least Rs:10,000 whenever salary data is added or updated in a table containing personnel information.
UNIQUE constraints-Avoids duplicates. It is a rule that forbids duplicate values in one or more columns within a table.
Referential Integrity constraints-You can define primary key and foreign key constraints to define relationships between tables.