If you want to build a career in data, software, or analytics, learning SQL commands is one of the most important skills. SQL is used in almost every company because it helps you store, manage, and read data easily. Before we go deep, let’s first understand the SQL full form — it stands for Structured Query Language.
In this simple and clear guide, you will learn about ddl commands, dml commands in sql, ddl dml, ddl dml dcl, and even ddl, dml, dcl, tcl in sql with easy examples. This article is also helpful for students preparing for sql interview questions.
What Are SQL Commands?
SQL commands are instructions used to communicate with a database. These commands help you create tables, insert records, update data, and control access.
All sql commands are divided into different groups. The most popular groups are:
- DDL (Data Definition Language)
- DML (Data Manipulation Language)
- DQL (Data Query Language)
- DCL (Data Control Language)
- TCL (Transaction Control Language)
Each group is used for a different purpose, and knowing them makes your database skills stronger.
1. DDL Commands in SQL (Data Definition Language)
DDL stands for Data Definition Language. These commands are used to define or change the structure of a database.
You will use ddl commands when you want to create, delete, or modify tables.
Here are the main ddl commands in sql:
1. CREATE
Used to create a new table.
sql
CREATE TABLE students (
id INT,
name VARCHAR(50),
age INT
);
2. ALTER
Used to change an existing table.
sql
ALTER TABLE students ADD email VARCHAR(100);
3. DROP
Used to delete a table permanently.
sql
DROP TABLE students;
4. TRUNCATE
Used to delete all data from a table but keep the table structure.
sql
TRUNCATE TABLE students;
5. RENAME
Used to change the table name.
sql
RENAME TABLE students TO student_data;
You have now seen all ddl commands with examples.
These ddl commands in sql change how the database looks and works.
2. DML Commands in SQL (Data Manipulation Language)
DML is used to work with the data inside the table.
If you want to add new data, update it, or delete it, you use dml commands in sql.
Here are the common commands:
1. INSERT
Adds new rows.
sql
INSERT INTO students (id, name, age)
VALUES (1, 'Rahul', 20);
2. UPDATE
Updates old data.
sql
UPDATE students SET age = 21 WHERE id = 1;
3. DELETE
Deletes specific rows.
sql
DELETE FROM students WHERE id = 1;
These are the most used dml commands in sql with examples, and they are important for jobs and sql interview questions.
3. DQL (Data Query Language)
DQL is used to fetch data from a table. The main command in DQL is:
sql
SELECT * FROM students;
This helps you read and understand data easily.
4. DCL (Data Control Language)
DCL controls access and permissions in the database.
1. GRANT
Gives access to a user.
sql
GRANT SELECT ON students TO user1;
2. REVOKE
Removes permission.
sql
REVOKE SELECT ON students FROM user1;
5. TCL (Transaction Control Language)
TCL handles transactions and ensures data safety.
1. COMMIT
Saves your changes.
sql
COMMIT;
2. ROLLBACK
Undo changes.
sql
ROLLBACK;
3. SAVEPOINT
Creates a save point.
sql
SAVEPOINT point1;
Complete Summary of DDL, DML, DQL, DCL, and TCL in SQL
The main SQL command types are DDL, DML, DQL, DCL, and TCL, and each one has a different purpose in database work. DDL (Data Definition Language) is used to change the table structure, such as creating, altering, or dropping tables. DML (Data Manipulation Language) works with the actual data inside the table, like inserting, updating, or deleting records. DQL (Data Query Language) focuses on reading data, and its main command is SELECT, which helps you fetch information from tables. DCL (Data Control Language) manages permissions and controls who can access or modify the data through commands like GRANT and REVOKE. TCL (Transaction Control Language) handles transactions and ensures data safety by using commands like COMMIT, ROLLBACK, and SAVEPOINT. By understanding these types clearly, you can easily explain ddl dml, ddl dml dcl, and ddl, dml, dcl, tcl in sql with examples in interviews or real database tasks.
Why These Commands Matter for Your Career?
These commands are asked again and again in sql interview questions, especially:
- What is DDL?
- What is DML?
- Explain ddl commands with examples.
- What is sql full form?
- What are dml commands in sql with examples?
Knowing these makes it easy to pass interviews for data analyst, developer, and engineering jobs.
Conclusion
Understanding SQL commands like DDL, DML, DQL, DCL, and TCL is one of the strongest foundations you can build for your career in technology. These commands help you work with data, manage databases, and perform real tasks that companies use every day. Whether you are preparing for interviews, improving your skills, or planning to grow in fields like analytics, development, or engineering, SQL is a must-learn skill.
If you want to take your learning even further, joining a data analyst course can help you master SQL along with other important tools used in the industry. With proper training and practice, you can confidently handle real-world data problems, clear interviews, and build a strong career in the data field.
FAQs
1. What is SQL full form?
The SQL full form is Structured Query Language. It is used to manage and read data in databases.
2. What are DDL commands?
DDL commands are used to create, update, and delete database structures like tables.
3. What are the main DML commands in SQL?
The main dml commands in sql are INSERT, UPDATE, and DELETE.
4. What is the difference between DDL and DML?
- DDL changes table structure.
- DML changes table data.
This difference is often asked in sql interview questions.
5. What is DCL in SQL?
DCL commands (GRANT, REVOKE) handle user permissions in the database.
6. What is TCL used for?
TCL commands are used to save or undo changes in a database.
7. Why are SQL commands important?
Because almost every company needs data management, and sql commands help in building, reading, and controlling data.
