SQL INNER JOIN

SQL INNER JOIN clause is used to select data from 2 (or more) tables, at least one match in both tables.

SQL INNER JOIN Clause Syntax

SELECT Table1.Column1, Table1.Column2, ... , Table2.Column1, Table2.Column2, ...
FROM Table1
INNER JOIN Table2
ON Table1.ColumnName = Table2.ColumnName

Note: SQL INNER JOIN is the default type of SQL JOIN. “JOIN” = “INNER JOIN”

SQL INNER JOIN Clause Example

Table: Employees

EmployeeId	FirstName	LastName	Department	Salary
203	Mazojys	Fxoj	Finance	78000
204	Jozzh	Lnanyo	Finance	45800
205	Syllauu	Dfaafk	Finance	57000
206	Gecrrcc	Srlkrt	Finance	62000

Table: Tickets

TicketID	TicketNo	EmployeeId
1	2349	203
2	2400	204
3	2438	205

Select all the employees with any tickets:

SELECT Employees.EmployeeId
           , Employees.FirstName
           , Employees.LastName
           , Tickets.TicketNo
FROM Employees
INNER JOIN Tickets
ON Employees.EmployeeId = Tickets.EmployeeId

The result will look like:

EmployeeId	FirstName	LastName	TicketNo
203	Mazojys	Fxoj	2349
204	Jozzh	Lnanyo	2400
205	Syllauu	Dfaafk	2438

Note: The employee whose EmployeeId is 206 doesn’t have any records matched in the table Tickets, so this employee will not in the result.

As mentioned above, “JOIN” = “INNER JOIN”, so, the following statement has the same result:

SELECT Employees.EmployeeId
           , Employees.FirstName
           , Employees.LastName
           , Tickets.TicketNo
FROM Employees
JOIN Tickets
ON Employees.EmployeeId = Tickets.EmployeeId

In most database systems, we can even write it shorter:

SELECT Employees.EmployeeId
           , Employees.FirstName
           , Employees.LastName
           , Tickets.TicketNo
FROM Employees, Tickets
WHERE Employees.EmployeeId = Tickets.EmployeeId