SQL INNER JOIN

INNER JOIN is the most frequently used join in SQL. These joins are also referred to as EQUIJOIN. It creates a new result set that comprises the matching records of the joined tables on the basis of joining ground. If the condition on the predicate meets then it will return the matched pair of rows of Table A and Table B.

  • Syntax of INNER JOIN –

SELECT column1 , column2 , column3 , ... , columnN FROM Table A
INNER JOIN
Table B ON TableA.column_name = TableB.column_name ;

Example – Consider these two tables the Product table and the Manager table.

Product Table

Category Region City Country Customer_ID Customer_name
Office Supplies Central Chicago United States SM-20950 Suzanne McNair
Technology East New York City United States AH-10465 Amy Hunt
Office Supplies East New York City United States AH-10465 Amy Hunt
Office Supplies East Dover United States EP-13915 Emily Phan
Office Supplies East Dover United States EP-13915 Emily Phan
Technology West Aurora United States TP-21565 Tracy Poddar
Office Supplies West Aurora United States TP-21565 Tracy Poddar
Office Supplies East Long Beach United States AR-10825 Anthony Rawles
Office Supplies West Pasadena United States HA-14920 Helen Andreada
Furniture West Pasadena United States HA-14920 Helen Andreada

 

Manager Table

Region Regional Manager
West Sadie Pawthorne
East Chuck Magee
Central Roxanne Rodriguez
South Fred Suzuki

Now, let us suppose we want to know the Regional managers of the cities. Below is the statement that shows the results.

SELECT A.Category,A.City,A.[Customer Name],A.Region,B.[Regional Manager]
FROM [dbo].[Products] AS A
INNER JOIN [dbo].[Manager] AS B
ON A.Region = B.Region;

 

This output is the small section of the output by executing the above query –

Category City Customer_ID Region Regional Manager
Office Supplies Chicago Suzanne McNair Central Roxanne Rodriguez
Technology New York City Amy Hunt East Chuck Magee
Office Supplies New York City Amy Hunt East Chuck Magee
Office Supplies Dover Emily Phan East Chuck Magee
Office Supplies Dover Emily Phan East Chuck Magee
Technology Aurora Tracy Poddar West Sadie Pawthorne
Office Supplies Aurora Tracy Poddar West Sadie Pawthorne
Office Supplies Long Beach Anthony Rawles East Chuck Magee
Office Supplies Pasadena Helen Andreada West Sadie Pawthorne
Furniture Pasadena Helen Andreada West Sadie Pawthorne

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