The LEFT JOIN keyword returns all records from the left table (table1), and the matched records from the right table (table2). The result is NULL from the right side, if there is no match.
LEFT JOIN table2
ON table1.column_name = table2.column_name;
SELECT employees.emp_no, employees.last_name, employees.first_name, salaries.salary
FROM `employees` LEFT JOIN salaries ON employees.emp_no=salaries.emp_no
Tester Usage Tips:
- Validate records from more than 1 table where all records from left table are fetched and matching records from right table are fetched. For example all students information left table and matching exam results in right table , if the students has not attended the exam null is fetched.