| DCL<\/td> | Data Control Language<\/td> | Controls database permissions and access<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n Let’s understand each category in detail.<\/p>\n\n\n\n
\n\n\n\n<\/span>1. DDL (Data Definition Language)<\/strong><\/span><\/h1>\n\n\n\nDDL commands are used to create, modify, and delete database objects such as tables, databases, indexes, and schemas.<\/p>\n\n\n\n Think of DDL as the commands used to design the structure of a database.<\/p>\n\n\n\n <\/span>Common DDL Commands<\/strong><\/span><\/h2>\n\n\n\n<\/span>CREATE<\/strong><\/span><\/h3>\n\n\n\nUsed to create new database objects.<\/p>\n\n\n\n Example:<\/p>\n\n\n\n CREATE TABLE Students (<\/p>\n\n\n\n StudentID INT,<\/p>\n\n\n\n Name VARCHAR(100),<\/p>\n\n\n\n Course VARCHAR(50)<\/p>\n\n\n\n This command creates a new table called Students.<\/p>\n\n\n\n
\n\n\n\n<\/span>ALTER<\/strong><\/span><\/h3>\n\n\n\nUsed to modify an existing table.<\/p>\n\n\n\n Example:<\/p>\n\n\n\n ALTER TABLE Students<\/p>\n\n\n\n ADD Email VARCHAR(100)<\/p>\n\n\n\n This adds a new email column to the Students table.<\/p>\n\n\n\n
\n\n\n\n<\/span>DROP<\/strong><\/span><\/h3>\n\n\n\nUsed to permanently remove a database object.<\/p>\n\n\n\n Example:<\/p>\n\n\n\n DROP TABLE Students<\/p>\n\n\n\n This deletes the Students table completely.<\/p>\n\n\n\n
\n\n\n\n<\/span>TRUNCATE<\/strong><\/span><\/h3>\n\n\n\nRemoves all records from a table while keeping its structure intact.<\/p>\n\n\n\n Example:<\/p>\n\n\n\n TRUNCATE TABLE Students;<\/p>\n\n\n\n All student data is removed, but the table remains.<\/p>\n\n\n\n
\n\n\n\n<\/span>When Is DDL Used?<\/strong><\/span><\/h2>\n\n\n\nDDL commands are commonly used when:<\/p>\n\n\n\n \n- Creating new databases<\/li>\n\n\n\n
- Designing application structures<\/li>\n\n\n\n
- Modifying tables<\/li>\n\n\n\n
- Managing database architecture<\/li>\n<\/ul>\n\n\n\n
\n\n\n\n<\/span>2. DML (Data Manipulation Language)<\/strong><\/span><\/h1>\n\n\n\nDML commands are used to manipulate data stored inside database tables.<\/p>\n\n\n\n Once a table is created using DDL, DML helps manage the records inside it.<\/p>\n\n\n\n <\/span>Common DML Commands<\/strong><\/span><\/h2>\n\n\n\n<\/span>INSERT<\/strong><\/span><\/h3>\n\n\n\nAdds new records into a table.<\/p>\n\n\n\n Example:<\/p>\n\n\n\n INSERT INTO Students<\/p>\n\n\n\n VALUES (101, ‘Rahul Sharma’, ‘Data Analytics’)<\/p>\n\n\n\n This inserts a new student record.<\/p>\n\n\n\n
\n\n\n\n<\/span>UPDATE<\/strong><\/span><\/h3>\n\n\n\nModifies existing records.<\/p>\n\n\n\n Example:<\/p>\n\n\n\n UPDATE Students<\/p>\n\n\n\n SET Course = ‘Full Stack Development’<\/p>\n\n\n\n WHERE StudentID = 101<\/p>\n\n\n\n This updates Rahul’s course.<\/p>\n\n\n\n
\n\n\n\n<\/span>DELETE<\/strong><\/span><\/h3>\n\n\n\nRemoves records from a table.<\/p>\n\n\n\n Example:<\/p>\n\n\n\n DELETE FROM Students<\/p>\n\n\n\n WHERE StudentID = 101<\/p>\n\n\n\n This deletes the student record.<\/p>\n\n\n\n
\n\n\n\n<\/span>When Is DML Used?<\/strong><\/span><\/h2>\n\n\n\nDML commands are used daily in applications for:<\/p>\n\n\n\n \n- User registration<\/li>\n\n\n\n
- Profile updates<\/li>\n\n\n\n
- Order processing<\/li>\n\n\n\n
- Customer management<\/li>\n\n\n\n
- Inventory tracking<\/li>\n<\/ul>\n\n\n\n
\n\n\n\n<\/span>3. DQL (Data Query Language)<\/strong><\/span><\/h1>\n\n\n\nDQL is used to retrieve data from a database.<\/p>\n\n\n\n The primary command in DQL is:<\/p>\n\n\n\n <\/span>SELECT<\/strong><\/span><\/h3>\n\n\n\nThis command fetches data from one or more tables.<\/p>\n\n\n\n Example:<\/p>\n\n\n\n SELECT * FROM Students;<\/p>\n\n\n\n This displays all student records.<\/p>\n\n\n\n
\n\n\n\n<\/span>Filtering Data<\/strong><\/span><\/h3>\n\n\n\nExample:<\/p>\n\n\n\n SELECT Name, Course<\/p>\n\n\n\n FROM Students<\/p>\n\n\n\n WHERE Course = ‘Data Analytics’<\/p>\n\n\n\n This retrieves students enrolled in Data Analytics.<\/p>\n\n\n\n
\n\n\n\n<\/span>Sorting Data<\/strong><\/span><\/h3>\n\n\n\nExample:<\/p>\n\n\n\n SELECT *<\/p>\n\n\n\n FROM Students<\/p>\n\n\n\n ORDER BY Name ASC;<\/p>\n\n\n\n This sorts students alphabetically.<\/p>\n\n\n\n
\n\n\n\n<\/span>Why Is DQL Important?<\/strong><\/span><\/h2>\n\n\n\nMost business reporting systems depend heavily on DQL commands.<\/p>\n\n\n\n Examples include:<\/p>\n\n\n\n |