SQL DELETE

Article Summary

The DELETE statement is used to remove one or more rows from a table. πŸ”Ή Basic Syntax ⚠️ Always use a WHERE clause to avoid deleting everything! πŸ”Ή Examples πŸ”Ή Delete All Rows (Be Cautious!) πŸ”Ή With Subqueries 🧠 Quick Recap Action Syntax Example Delete with condition DELETE FROM table WHERE ... Delete all rows […]

The DELETE statement is used to remove one or more rows from a table.

πŸ”Ή Basic Syntax

DELETE FROM table_name
WHERE condition;

⚠️ Always use a WHERE clause to avoid deleting everything!

πŸ”Ή Examples

-- Delete a specific employee
DELETE FROM employees
WHERE employee_id = 101;

-- Delete all employees from the IT department
DELETE FROM employees
WHERE department = 'IT';

πŸ”Ή Delete All Rows (Be Cautious!)

-- Delete all rows (but keep the table)
DELETE FROM employees;

-- Oracle tip: Use TRUNCATE for faster delete (no WHERE allowed)
TRUNCATE TABLE employees;

πŸ”Ή With Subqueries

-- Delete employees who are not assigned to any department
DELETE FROM employees
WHERE department_id NOT IN (
  SELECT id FROM departments
);

🧠 Quick Recap

ActionSyntax Example
Delete with conditionDELETE FROM table WHERE ...
Delete all rowsDELETE FROM table;
Fast delete (Oracle)TRUNCATE TABLE table_name;
Delete using subqueryDELETE WHERE col IN (SELECT ...)

βœ… Use DELETE to clean up dataβ€”carefully!

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