What is the difference between check and domain constraint in database?

Question

I am studying relational database. While reading about the constraint the domain constraint and check seemed similar to me. What are the exact differences between them?

Answer 1

Domain constraints are a user-defined data type which is a definition of a valid set of values for an attribute and we can define them like this: Domain Constraint = data type + Constraints (NOT NULL / CHECK / DEFAULT)

As you can see CHECK is one of the ways in which a domain constraint can be applied.

For Example: Let's say, I have a table called student_info and I want to add a field called stu_id whose value should always be greater than 100, then the domain constraint will look like this

create domain id_value int
constraint id_test
check(value > 100);

create table student_info (
stu_id id_value PRIMARY KEY,
stu_name varchar(30),
stu_age int
);

Here id_value is of type int and has a constraint to check if the value is greater than 100 or not.

Reference.