The Left Outer Join

Read the first article in this series here. 

The visual reprsentation of the Left Outer Join is as shown in picture 1. In picture 1  a represents CUSTOMERS table and b represents TRANSACTION table.

A simple query would be like this

SELECT customers.customer_no, customers.customer_Name, transaction.Time_Stamp

FROM customers

LEFT OUTER JOIN transaction

on customers.Customer.no = transaction.Customer.no

The table designs are revisited .

CUSTOMERS Table

TRANSACTION Table

Let us take a look at the records of both the tables .

CUSTOMERS Table :

This implies ,the result set of a query that uses left outer join will have all records from table a and those that intersect table a from table b or those that have a matching value in table a for the field on which the left outer join is made ;in this case the customer _no field.

The picture 2 above is the representation of how the result set is arrived at for the query ,using Left Outer Join, in discussion.