LEFT JOIN
The LEFT JOIN
command combines matching rows with rows from the left-side table.
Syntax
SELECT column_name(s)
FROM table_1
LEFT JOIN table_2
ON table_1.column_name = table_2.column_name;
Every row in the left table is returned in the result set. If the join condition is not met, then NULL
values are used to fill in the columns from the right table.
Example
To create a result set of every row in the students
table combined with the transfer_data
table where student IDs match. And if the join condition is not met, then NULL
values are used to fill in the columns from the transfer_data
table.
SELECTstudents.first_name,students.last_name,students.overall_gpa,transfer_data.overal_gpaFROM studentsLEFT JOIN transfer_dataON students.student_id = transfer_data.student_id;
The result set will only include last name, first name, and both GPAs.