SQL INNER JOIN

SQL INNER JOIN clause is used to combine and extract rows from two or more tables by joining common field. This common field column is compared by comparison operators like =, <, >, <=, >= or <>. INNER JOIN is also called as equi-join and returns those rows with equal value in join column. INNER JOIN and JOIN both are same and provides similar output.

Syntax

SELECT columnName(s)

FROM Table1 INNER JOIN Table2

ON Table1.columnName = Table2.columnName

Refer below image to understand INNER JOIN, here green part is output for INNER JOIN.

Here we will consider one example for INNER JOIN condition where we will use two tables named as SalesDetails and ClientDetails.

Table Name: SalesDetails

Table Name: ClientDetails

From above two tables, we need columns OrderID and OrderDate from SalesDetails table and one column ClientName from ClientDetails table and sorted in ascending order by OrderDate column. So to get the output from two tables we will use INNER JOIN query as given below.

SELECT OrderID, ClientName, OrderDate
FROM SalesDetails INNER JOIN ClientDetails 
ON SalesDetails.ClientID = ClientDetails.ClientID
ORDER BY OrderDate

You can see the output by joining two tables in result pane where required data is sorted by OrderDate column.

Let’s consider one more example with greater than operator (>) where OrderDate column is greater than 13-Aug-2015.

SELECT OrderID, ClientName, OrderDate
FROM SalesDetails JOIN ClientDetails 
ON SalesDetails.ClientID = ClientDetails.ClientID
AND OrderDate > '2015-08-13'

So, we have four such records as shown above.

Also Refer:

• SQL JOINS
• SQL LEFT JOIN
• SQL RIGHT JOIN
• SQL FULL JOIN
• SQL CROSS JOIN

Reference: Manzoor Siddiqui [www.SQLServerLog.com]