Transactional Control Language (TCL) commands are used to manage transactions in the database. These are used to manage the changes made to the data in a table by DML statements.
SQL command:
commit - saves any transaction into the database permanently.
Roll back - Restores the database to last commit state
Save point - Temporarily save a transaction so that we can rollback.

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. The privileges are required for performing all the database operations such as creating sequences, views of tables etc.
SQL commands:
Grant - Grants permission to one or more users to perform specific tasks
Revoke - Withdraws the access permission given by the GRANT Statement.

A Data manipulation language (DML) is a computer programming language used for adding, removing and modifying data in a database, In SQL the data manipulation language comprises the SQL - data change statements, which modify stored data but not the schema of the database table.
After the database schema has been specified and the database has been created, the data can be manipulated using a set of procedures which are expressed by DML.
By Data Manipulation,
1. Insertion of new information into the database
2. Retrieval of information stored in a database
3. Deletion of information from the database
4. Modification of data stored in the database.

The Data Definition Language (DDL) consist of SQL statements used to define the database structure or schema. It simply deals with descriptions of the database schema and is used to create and modify the structure of database objects in databases.
DDL commands include Create Table, ALTER TABLE, drop table, Truncate TABLE.
Functions:
1. It should identify the type of data division such as data item, segment, record and database file.
2. It gives a unique name to each data item type, record type, file type and database.
3. It should specify the proper data type.
4. It should define the size of the data item.
5. It may define the range of values that a data item may use.
6. It may specify privacy locks for preventing unauthorized data entry.

(i) DDL - Data Definition Language
(ii) DML - Data Manipulation Language
(iii) DCL - Data Control Language
(iv) TCL - Transaction Control Language
(v) DQL - Data Query Language

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.

One of the most important tasks when working with SQL is to generate Queries and retrieve data. A Query is a command given to get a desired result from the database table. The SELECT command is used to query or retrieve data from a table in the database. It is used to retrieve a subset of records from one or more tables. The SELECT command can be used in various forms:
Syntax of SELECT command:
SELECT < column-list > FROM < table-name > ;
(i) Table-name is the name of the table from which the information is retrieved.
(ii) Column-list includes one or more columns from which data is retrieved.

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.

The SQL provides a predetermined set of commands to work on databases.

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

(i) INSERT:
INSERT INTO <table-name>
[column-list] VALUES (values);
(ii) DELETE:
DELETE FROM table-name WHERE condition;
(iii) UPDATE:
UPDATE <table-name > SET column-name = value, column-name = value, ... WHERE condition;

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) It should identify the type of data division such as data item, segment, record and database file.
(ii) It gives a unique name to each data item type, record type, file type and data base.
(iii) It should specify the proper data type.
(iv) It should define the size of the data item.
(v) It may define the range of values that a data item may use.
(vi) It may specify privacy locks for preventing unauthorized data entry.

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

(i) The data in RDBMS, is stored in database objects, called Tables. A table is a collection of related data entries and it consist of rows and columns.
(ii) A field is a column in a table that is designed to maintain specific related information about every record in the table. It is a vertical entity that contains all information associated with a specific field in a table. The fields in a student table may be of the type AdmnNo, StudName, StudAge, StudClass, Place etc
(iii) A Record is a row, which is a collection of related fields or columns that exist in a table. A record is a horizontal entity in a table which represents the details of a particular student in a student table