Snippet Name: LEFT JOIN example and syntax
Description: The LEFT JOIN (also called LEFT OUTER JOIN) keyword returns all rows from the left table (table_name1), even if there are no matches in the right table (table_name2).
The result of a left outer join (or simply left join) for table A and B always contains all records of the "left" table (A), even if the join-condition does not find any matching record in the "right" table (B). This means that if the ON clause matches 0 (zero) records in B, the join will still return a row in the result—but with NULL in each column from B. This means that a left outer join returns all the values from the left table, plus matched values from the right table (or NULL in case of no matching join predicate).
Also see:
» ANSI Joins: FULL JOIN
» ANSI Joins: OUTER JOIN
» ANSI Joins: CROSS JOIN
» ANSI Joins: INNER JOIN
» Self-join example and syntax
» FULL JOIN example and syntax
» RIGHT JOIN example and syntax
» INNER JOIN example and syntax
Comment: (none)
Language: PL/SQL
Highlight Mode: PLSQL
Last Modified: March 07th, 2009
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SELECT column_name(s)
FROM table_name1
LEFT JOIN table_name2
ON table_name1.column_name=table_name2.column_name
-- or
SELECT *
FROM employee LEFT OUTER JOIN department
ON employee.DepartmentID = department.DepartmentID
-- for example:
SELECT Person.LastName, Person.FirstName, Sales.OrderNo
FROM Person
LEFT JOIN Sales
ON Person.P_Id=SalesP_Id
ORDER BY Person.LastName |
