Check Constraint: This constraint helps to set a limit value placed for a field. When we define a check constraint on a single column, it allows only the restricted values on that field. Example showing check constraint in the student table:
CREATE TABLE Student
(
Admno integer NOT NULL PRIMARY KEY
Name char(20) NOT NULL,
Gender char(1),
Age integer (CHECK<=19), ⟶ Check Constraint
Place char(10),
);
In the above example the check constraint is set to Age field where the value of Age must be less than or equal to 19.

Table Constraint: When the constraint is applied to a group of fields of the table, it is known as Table constraint. The table constraint is normally given at the end of the table definition. Let us take a new table namely Student with the following fields Admno, Firstname, Lastname, Gender, Age, Place:
Create Table Student 1
(
Admno integer NOT NULL,
Firstname char(20),
Lastname char(20),
Gender char(1),
Age integer,
Place char(10),
PRIMARY KEY (Firstname, Lastname) ⟶ Table constraint
);
In the above example, the two fields, Firstname and Lastname are defined as Primary key which is a Table constraint.

(i) char (Character)
(ii) varchar
(iii) dec (Decimal)
(iv) numeric
(v) int (Integer)
(vi) smallint
(vii) float
(viii) real
(ix) double

Data control language: A Data Control Language (DCL) is a programming language used to control the access of data stored in a database. It is used for controlling privileges in the database (Authorization). The privileges are required for performing all the database operations such as creating sequences, views of tables etc.
SQL commands which come under Data Control Language are:

(i) Unique Constraint
(ii) Primary Key Constraint
(iii) Default Constraint
(iv) Check Constraint