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Chapter 35: JOIN
Introduction
JOIN is a method of combining (joining) information from two tables. The result is a stitched set of
columns from both tables, defined by the join type (INNER/OUTER/CROSS and
LEFT/RIGHT/FULL, explained below) and join criteria (how rows from both tables relate).
A table may be joined to itself or to any other table. If information from more than two tables needs
to be accessed, multiple joins can be specified in a FROM clause.
Syntax
• [ { INNER | { { LEFT | RIGHT | FULL } [ OUTER ] } } ] JOIN
Remarks
Joins, as their name suggests, are a way of querying data from several tables in a joint fashion,
with the rows displaying columns taken from more than one table.
Examples
Basic explicit inner join
A basic join (also called "inner join") queries data from two tables, with their relationship defined in
a join clause.
The following example will select employees' first names (FName) from the Employees table and
the name of the department they work for (Name) from the Departments table:
SELECT Employees.FName, Departments.Name
FROM Employees
JOIN Departments
ON Employees.DepartmentId = Departments.Id
This would return the following from the example database:
Employees.FName Departments.Name
James HR
John HR
Richard Sales
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