"LEFT OUTER JOIN ... ON" - Writing Queries with Left Outer Joins in SQL Server


How To Write a Query with a Left Outer Join in SQL Server?

✍: FYIcenter.com


If you want to query from two tables with a left outer join, you can use the LEFT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a left outer join from two tables: fyi_links and fyi_rates. The join condition is that the id in the fyi_links table equals to the id in the fyi_rates table:

SELECT l.id, l.url, r.comment FROM fyi_links l 
   LEFT OUTER JOIN fyi_rates r ON l.id = r.id
id      url                     comment
101     dev.fyicenter.com       The best
102     dba.fyicenter.com       Well done
103     sqa.fyicenter.com       Thumbs up
104     www.mysql.com           NULL
105     www.oracle.com          NULL
106     www.php.net             NULL
107     www.winrunner.com       NULL

Note that a left outer join may return extra rows from the first (left) table that do not satisfy the join condition. In those extra rows, columns from the second (right) table will be given null values.

The extra rows returned from the left outer join in this example represents links that have no rates in the above example.


"RIGHT OUTER JOIN ... ON" - Writing Queries with Right Outer Joins in SQL Server

Defining and Using Table Alias Names in SQL Server

Using SELECT Statements with Joins and Subqueries in SQL Server

⇑⇑ SQL Server Database Tutorials

2016-10-30, 1872🔥, 0💬