INNER JOIN

An inner join is a type of join operation used in relational databases to retrieve data from two or more tables based on a common column, or columns, between them. It returns only the rows that have matching values in both tables being joined. In other words, an inner join combines rows from two tables where the specified columns have matching values.

Here's the basic syntax for performing an inner join in SQL:

SELECT columns

FROM table1 INNER JOIN table2

ON table1.column = table2.column;

Let's break down the components of this syntax:

SELECT columns: Specify the columns you want to retrieve from the result set. You can select columns from either or both of the joined tables.
FROM table1: Specify the first table from which you want to retrieve data.
INNER JOIN table2: Indicate that you want to perform an inner join with the second table (table2).

ON table1.column = table2.column: This is the join condition that specifies how the tables are related. You specify the columns from both tables that should have matching values. SQL inner join

Example: SQL INNER JOIN between two tables

Here is an example of inner join in SQL between two tables.

Sample table: foods

+---------+--------------+-----------+------------+
| ITEM_ID | ITEM_NAME    | ITEM_UNIT | COMPANY_ID |
+---------+--------------+-----------+------------+
| 1       | Chex Mix     | Pcs       | 16         |
| 6       | Cheez-It     | Pcs       | 15         |
| 2       | BN Biscuit   | Pcs       | 15         |
| 3       | Mighty Munch | Pcs       | 17         |
| 4       | Pot Rice     | Pcs       | 15         |
| 5       | Jaffa Cakes  | Pcs       | 18         |
| 7       | Salt n Shake | Pcs       |            |
+---------+--------------+-----------+------------+

Sample table: company

+------------+---------------+--------------+
| COMPANY_ID | COMPANY_NAME  | COMPANY_CITY |
+------------+---------------+--------------+
| 18         | Order All     | Boston       |
| 15         | Jack Hill Ltd | London       |
| 16         | Akas Foods    | Delhi        |
| 17         | Foodies.      | London       |
| 19         | sip-n-Bite.   | New York     |
+------------+---------------+--------------+

company_id of foods and company table must be same,

the following SQL statement can be used :

SQL Code:

SELECT foods.item_name,foods.item_unit,
company.company_name,company.company_city
FROM foods
INNER JOIN company
ON foods.company_id =company.company_id;

ITEM_NAME                 ITEM_ COMPANY_NAME              COMPANY_CITY
------------------------- ----- ------------------------- --------------
Chex Mix                  Pcs   Akas Foods                Delhi
Cheez-It                  Pcs   Jack Hill Ltd             London
BN Biscuit                Pcs   Jack Hill Ltd             London
Mighty Munch              Pcs   Foodies.                  London
Pot Rice                  Pcs   Jack Hill Ltd             London
Jaffa Cakes               Pcs   Order All                 Boston