SQL Full Outer Join Using Where Clause

A SQL join statement is used to combine rows or information from two or more than two tables on the basis of a common attribute or field. There are basically four types of JOINS in SQL.

In this article, we will discuss about FULL OUTER JOIN using WHERE clause.

Consider the two tables below:

Sample Input Table 1 : 

PURCHASE INFORMATION
Product_ID	Mobile_Brand	Cost (INR)	Customer_Name
1	OnePlus Nord 5G	30,000	Rishabh
2	Samsung Galaxy M51	28,000	Srishti
3	iPhone 12 Pro	1,28,000	Aman
4	Samsung Galaxy S20	55,000	Harsh
5	Realme X50 Pro	40,000	Manjari

Sample Input Table 2 :

CUSTOMER INFORMATION
Customer_ID	Customer_Name	E_Mail Address
1	Srishti	abc@gmail.com
2	Rajdeep	def@gmail.com
3	Aman	xxx@gmail.com
4	Pooja	xyz@gmail.com

FULL OUTER JOIN : Full Join provides result with concatenation of LEFT JOIN and RIGHT JOIN. The result will contain all the rows from both Table 1 and Table 2. The rows having no matching in result table will have NULL values. 

SELECT * FROM Table1
FULL OUTER JOIN Table2
ON Table1.column_match=Table2.column_match;

Table1: First Table in Database.
Table2: Second Table in Database.
column_match: The column common to both the tables.

Sample Output :

RESULTS
Product_ID	Mobile_Brand	Cost (INR)	Customer_Name	Customer_ID	Customer_Name	E_Mail Address
1	OnePlus Nord 5G	30,000	Rishabh	NULL	NULL	NULL
2	Samsung Galaxy M51	28,000	Srishti	1	Srishti	abc@gmail.com
3	iPhone 12 Pro	1,28,000	Aman	3	Aman	xxx@gmail.com
4	Samsung Galaxy S20	55,000	Harsh	NULL	NULL	NULL
5	Realme X50 Pro	40,000	Manjari	NULL	NULL	NULL
NULL	NULL	NULL	NULL	2	Rajdeep	def@gmail.com
NULL	NULL	NULL	NULL	4	Pooja	xyz@gmail.com

FULL OUTER JOIN using WHERE CLAUSE : The use of WHERE clause with FULL OUTER JOIN helps to retrieve all those rows which have no entry matching on joining both the tables having NULL entry. 

SELECT * FROM Table1
FULL OUTER JOIN Table2
ON Table1.column_match=Table2.column_match
WHERE Table1.column is NULL
OR Table2.column is NULL;

Table1: First Table in Database.
Table2: Second Table in Database.
column_match: The column common to both the tables.
column: The column having NULL value after Full Outer Join

The above Query returns only those customer who bought mobile phones and don’t have any record saved in Customer Information Table as well as the customer information who didn’t buy any product.

SQL QUERY FOR THE SAMPLE INPUTS : We have considered a Customer and Purchase Information of Mobile Phones from an E-Commerce site during Big Billion Days. The Database E-Commerce has two tables one has information about the Product and the other one have information about the Customer. Now, we will perform FULL OUTER JOIN between these two tables to concatenate them into a single table and get complete data about the customers and the products they  purchased from the site.

BASIC SQL QUERY :

1. Creating a Database

CREATE DATABASE database_name;

2. Creating a Table

CREATE TABLE Table_name(
col_1 TYPE col_1_constraint,
col_2 TYPE col_2 constraint
.....
)

col: Column name
TYPE: Data type whether an integer, variable character, etc
col_constraint: Constraints in SQL like PRIMARY KEY, NOT NULL, UNIQUE, REFERENCES, etc

3. Inserting into a Table

INSERT INTO Table_name
VALUES(val_1, val_2, val_3, ..........)

val: Values in particular column

4. View The Table

SELECT * FROM Table_name

For more information regarding SQL syntaxes visit our website SQL Tutorial.

Output :

1. Customer Information and Purchase Information Table

Purchase Information Table

Customer Information Table

2. Full Outer Join 

Result Table of FULL OUTER JOIN

3. Full Outer Join with WHERE clause

FULL OUTER JOIN  with WHERE clause Resultant Table

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