LEFT JOIN, RIGHT JOIN Operations

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Combines source-table records when used in any FROM clause.

Syntax

FROM table1 [ LEFT | RIGHT ] JOIN table2
ON table1.field1 compopr table2.field2

The LEFT JOIN and RIGHT JOIN operations have these parts:

Part Description
table1, table2 The names of the tables from which records are combined.
field1, field2 The names of the fields that are joined. The fields must be of the same data type and contain the same kind of data, but they don't need to have the same name.
compopr Any relational comparison operator: "=," "<," ">," "<=," ">=," or "<>."

Remarks

Use a LEFT JOIN operation to create a left outer join. Left outer joins include all of the records from the first (left) of two tables, even if there are no matching values for records in the second (right) table.

Use a RIGHT JOIN operation to create a right outer join. Right outer joins include all of the records from the second (right) of two tables, even if there are no matching values for records in the first (left) table.

For example, you could use LEFT JOIN with the Departments (left) and Employees (right) tables to select all departments, including those that have no employees assigned to them. To select all employees, including those who aren't assigned to a department, you would use RIGHT JOIN.

The following example shows how you could join the Categories and Products tables on the CategoryID field. The query produces a list of all categories, including those that contain no products:

SELECT CategoryName,
ProductName
FROM Categories LEFT JOIN Products
ON Categories.CategoryID = Products.CategoryID;

In this example, CategoryID is the joined field, but it isn't included in the query results because it isn't included in the SELECT statement. To include the joined field, enter the field name in the SELECT statement — in this case, Categories.CategoryID.

Notes