🟢 Easy
CRUD
CREATE, READ, UPDATE, DELETE
🟢 Easy
INSERT
INSERT adds new rows to a table by specifying columns and their corresponding values.
SQL
INSERT INTO employees
(employee_id, first_name, salary)
VALUES
(101, 'John', 75000);
🟡 Intermediate
UPDATE
UPDATE modifies existing rows. Always include a WHERE clause, otherwise every row in the table will be updated.
SQL
UPDATE employees
SET salary = 80000
WHERE employee_id = 101;⚠️ Warning
Without WHERE, every row updates!
UPDATE employees SET salary=80000;
🟢 Easy
DELETE
DELETE removes rows from a table. Use WHERE to target specific rows, or the whole table will be emptied.
SQL
DELETE FROM employees
WHERE employee_id = 101;