delete-data.md

1. DELETE:

Explanation: DELETE is used to delete existing rows from a table.

Syntax:

DELETE
FROM
    table_name1
WHERE
    column_name1 = specific_value1;

Example:

DELETE
FROM
    salary_appraisal
WHERE
    emp_no = '100010';

Result:

2 rows affected. (Query took 0.0910 seconds.)

2. DELETE JOIN:

Explanation: DELETE JOIN is used to delete rows from a table based on a join with another table.

Syntax:

DELETE
    table_name1
FROM
    table_name1
JOIN table_name2 ON table_name1.column_name1 = table_name2.column_name2;

Example:

DELETE
    salary_appraisal
FROM
    salary_appraisal
JOIN employees ON salary_appraisal.emp_no = employees.emp_no;

Result:

3 rows affected. (Query took 0.0950 seconds.)

3. Deleting all rows from a table:

DELETE FROM table_name;

Example:

DELETE FROM employees;

Result:

All rows from the "employees" table will be deleted.

4. Deleting data using a subquery:

DELETE FROM table_name WHERE column_name IN (SELECT column_name FROM other_table WHERE condition);

Example:

DELETE FROM employees WHERE emp_id IN (SELECT emp_id FROM terminated_employees);

Result:

All rows from the "employees" table where the "emp_id" column matches any value from the "terminated_employees" table will be deleted.