Left Join in SQL
January 9, 2023 2023-01-10 6:01Left Join in SQL
Subhajit The SQL LEFT JOIN returns all rows from the left table, even if there are no matches in the right table. This means that if the ON clause matches 0 (zero) records in the right table; the join will still return a row in the result, but with NULL in each column from the right table.
Below is the student table which has a row in which the department column is NULL.
The department table will be as follows
Now if we apply the LEFT JOIN as follows
SELECT STUDENT.FirstName, STUDENT.LastName, DEPARTMENT.DepartmentName
FROM STUDENT LEFT JOIN DEPARTMENT
ON STUDENT.DepartmentId = DEPARTMENT.DepartmentId
We will get the below result where we will get all the matched rows as well as unmatched rows from the left table and all the matched rows from the right table and NULL value for the unmatched rows.
Please comment and share if you like this post and tell us about how we can enhance our posts. Thanks.
