LEFT JOIN
keyword returns all records from the left table (table 1), and the matching records from the right table (table 2). The result is 0 records from the right side, if there is no match.
NOTE
In some databases LEFT JOIN is called LEFT OUTER JOIN
Here is the sample of Engineer table
id | fullname | title | department | manager |
---|---|---|---|---|
1 | Eric Brown | Software Engineer | IT | Frank Martin |
2 | Brandon Hart | DevOps Engineer | IT | Justin Martin |
3 | Connor Langdon | Software Engineer | IT | Lucas Scott |
Here is the sample of Certificate table
id | engineerid | certificatename | certificatedate |
---|---|---|---|
1 | 1 | Docker Certified Associate | 2020-05-05 |
2 | 2 | Certified Kubernetes Administrator | 2021-07-03 |
Examples / Outputs
1SELECT e.id, e.fullname "Full Name",
2c.certificatename "Certificate Name"
3FROM engineer AS e
4LEFT JOIN certificate as c
5ON e.Id=c.engineerid;
id | Full Name | Certificate Name |
---|---|---|
1 | Eric Brown | Docker Certified Associate |
2 | Brandon Hart | Certified Kubernetes Administrator |
3 | Connor Langdon |