Left Outer Join in SQL - sql - sql tutorial - learn sql




  • The SQL LEFT JOIN returns all rows from the left table, even if there are no matches in the right table.
  • This means that a left join returns all the values from the left table, plus matched values from the right table or NULL in case of no matching join predicate.
 representation of join types
  • Let's assume that we have the following two tables,

Table Store_Information

Store_Name Sales Txn_Date
Los Angeles 1500 Jan-05-1999
San Diego 250 Jan-07-1999
Los Angeles 300 Jan-08-1999
Boston 700 Jan-08-1999

Table Geography

Region_Name Store_Name
East Boston
East New York
West Los Angeles
West San Diego
  • We want to find out sales by store, and we want to see the results for all stores regardless whether there is a sale in the Store_Information table.
  • To do this, we can use the following SQL statement using LEFT OUTER JOIN:
SELECT A1.Store_Name STORE, SUM(A2.Sales) SALES 
FROM Geography A1 
LEFT OUTER JOIN Store_Information A2 
ON A1.Store_Name = A2.Store_Name 
GROUP BY A1.Store_Name;

Result:

STORE SALES
Los Angeles 1800
San Diego 250
New York NULL
Boston 700
  • By using LEFT OUTER JOIN, all four rows in the Geography table is listed.
  • Since there is no match for "New York" in the Store_Information table, the Sales total for "New York" is NULL. Note that it is NULL and not 0, as NULL indicates there is no match.
sql tutorial , pl sql tutorial , mysql tutorial , oracle tutorial , learn sql , sql server tutorial

SQL Joins

SQL All Joins
Tags : sql tutorial , pl sql tutorial , mysql tutorial , oracle tutorial , learn sql , sql server tutorial

All SQL Joins

All SQL Joins

This tutorial provides more the basic needs and informations on sql tutorial , pl sql tutorial , mysql tutorial , sql server , sqlcode , sql queries , sql , sql formatter , sql join , w3schools sql , oracle tutorial , mysql , pl sql , learn sql , sql tutorial for beginners , sql server tutorial , sql query tutorial , oracle sql tutorial , t sql tutorial , ms sql tutorial , database tutorial , sql tutorial point , oracle pl sql tutorial , oracle database tutorial , oracle tutorial for beginners , ms sql server tutorial , sql tutorial pdf

Related Searches to Left Outer Join in SQL

Adblocker detected! Please consider reading this notice.

We've detected that you are using AdBlock Plus or some other adblocking software which is preventing the page from fully loading.

We don't have any banner, Flash, animation, obnoxious sound, or popup ad. We do not implement these annoying types of ads!

We need money to operate the site, and almost all of it comes from our online advertising.

Please add wikitechy.com to your ad blocking whitelist or disable your adblocking software.

×