INSERT adds new rows, UPDATE modifies existing rows, DELETE removes rows. These are Data Manipulation Language (DML) statements that change table data.

**INSERT Statement:**

Adds new rows to table:

• INSERT INTO table (col1, col2) VALUES (val1, val2)

• INSERT multiple rows: VALUES (val1, val2), (val3, val4)

• INSERT from SELECT: INSERT INTO table SELECT ...

**UPDATE Statement:**

Modifies existing rows:

• UPDATE table SET col1 = val1 WHERE condition

• Always use WHERE to avoid updating all rows

• Can update multiple columns at once

• Can use subqueries in SET clause

**DELETE Statement:**

Removes rows from table:

• DELETE FROM table WHERE condition

• Always use WHERE to avoid deleting all rows

• Cannot be undone without transaction

• Respects foreign key constraints

INSERT/UPDATE/DELETE are the foundation of CRUD operations in every application. Critical for backend developers, DBAs, and data engineers. Mistakes can cause data loss, so understanding transactions and constraints is essential.

Data modification statements are essential for every application - user registration (INSERT), profile updates (UPDATE), account deletion (DELETE). Understanding safe modification practices prevents data loss and maintains referential integrity.