What is the difference between left outer join and right outer join?

Asked By: Marbelys Vellido | Last Updated: 18th January, 2020
Category: technology and computing databases
4.4/5 (122 Views . 9 Votes)
The key difference between a left outer join, and a right outer join is that in a left outer join it's the table in the FROM clause whose all rows are returned. Whereas, in a right outer join we are returning all rows from the table specified in the join clause.

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Besides, what is the difference between left join and outer join?

The main difference between the Left Join and Right Join lies in the inclusion of non-matched rows. Left outer join includes the unmatched rows from the table which is on the left of the join clause whereas a Right outer join includes the unmatched rows from the table which is on the right of the join clause.

Likewise, what is the difference between right join and right outer join? There is no difference between RIGHT JOIN and RIGHT OUTER JOIN . Both are the same. That means that LEFT JOIN and LEFT OUTER JOIN are the same.

Also know, what's the difference between a left outer join Inner join and a right outer join?

The main difference between RIGHT OUTER join and LEFT OUTER join, as there name suggest, is the inclusion of non-matched rows. In short result of LEFT outer join is INNER JOIN + unmatched rows from LEFT table and RIGHT OUTER join is INNER JOIN + unmatched rows from the right-hand side table.

Which is faster inner or left join?

A LEFT JOIN is absolutely not faster than an INNER JOIN . In fact, it's slower; by definition, an outer join ( LEFT JOIN or RIGHT JOIN ) has to do all the work of an INNER JOIN plus the extra work of null-extending the results.

29 Related Question Answers Found

Which SQL JOIN is faster?

Well, in general INNER JOIN will be faster because it only returns the rows matched in all joined tables based on the joined column. But LEFT JOIN will return all rows from a table specified LEFT and all matching rows from a table specified RIGHT.

Which table is left in left join?

The left table is the table that is in the FROM clause, or left of the join condition, the join clause here. And a right table is on the right side of the join clause. When we speak of a left outer join, what we're saying is, take all the rows from the left table, and join them to rows on the right table.

IS LEFT JOIN inner or outer?

LEFT JOIN is same as LEFT OUTER JOIN - (Select records from the first (left-most) table with matching right table records.) RIGHT JOIN is same as RIGHT OUTER JOIN - (Select records from the second (right-most) table with matching left table records.) Inner join: Only show rows, when has it data from both of the tables.

Why use left or right join?

The only reason I can think of to use RIGHT OUTER JOIN is to try to make your SQL more self-documenting. You might possibly want to use left joins for queries that have null rows in the dependent (many) side of one-to-many relationships and right joins on those queries that generate null rows in the independent side.

What are different types of joins?


A JOIN is a means for combining columns from one (self-join) or more tables by using values common to each. ANSI-standard SQL specifies five types of JOIN : INNER , LEFT OUTER , RIGHT OUTER , FULL OUTER and CROSS . As a special case, a table (base table, view, or joined table) can JOIN to itself in a self-join.

What does LEFT JOIN mean?

The SQL LEFT JOIN returns all rows from the left table, even if there are no matches in the right table. This means that if the ON clause matches 0 (zero) records in the right table; the join will still return a row in the result, but with NULL in each column from the right table.

How does LEFT JOIN work?

The LEFT JOIN clause allows you to query data from multiple tables. It returns all rows from the left table and the matching rows from the right table. In short, the LEFT JOIN clause returns all rows from the left table (T1) and matching rows or NULL values from the right table (T2).

What is left outer join with example?

About LEFT OUTER Join Operations. The result set of a LEFT OUTER join contains all rows from both tables that meet the WHERE clause criteria, same as an INNER join result set. This is the same as using a WHERE NOT EXISTS sub-query. For example, select all of the teams that do not have players in the PLAYERS table.

Are left and right joins the same?

Table you are joining is 'RIGHT'. LEFT JOIN: Take all items from left table AND (only) matching items from right table. RIGHT JOIN: Take all items from right table AND (only) matching items from left table. (INNER) JOIN: Returns records that have matching values in both tables.

What are left and right joins?


An SQL JOIN clause is used to combine rows from two or more tables, based on a common field between them. LEFT JOIN: returns all rows from the left table, even if there are no matches in the right table. RIGHT JOIN: returns all rows from the right table, even if there are no matches in the left table.

What is inner join outer join?

In SQL, a join is used to compare and combine — literally join — and return specific rows of data from two or more tables in a database. An inner join finds and returns matching data from tables, while an outer join finds and returns matching data and some dissimilar data from tables.

What is a right outer join in a SQL query?

SQL - RIGHT JOINS. This means that if the ON clause matches 0 (zero) records in the left table; the join will still return a row in the result, but with NULL in each column from the left table.

What is the function of left outer join?

A LEFT OUTER JOIN is one of the JOIN operations that allow you to specify a join clause. It preserves the unmatched rows from the first (left) table, joining them with a NULL row in the shape of the second (right) table.

What does left outer join mean in SQL?

SQL OUTER JOINleft outer join
SQL left outer join is also known as SQL left join. SQL left outer join returns all rows in the left table (A) and all the matching rows found in the right table (B). It means the result of the SQL left join always contains the rows in the left table.

What does inner join mean in SQL?


What is Inner Join in SQL? The INNER JOIN selects all rows from both participating tables as long as there is a match between the columns. An SQL INNER JOIN is same as JOIN clause, combining rows from two or more tables. Here is an example of inner join in SQL between two tables.

How does right outer join work?

The RIGHT JOIN combines data from two or more tables. The RIGHT JOIN clause starts selecting data from the right table and matching with the rows from the left table. The RIGHT JOIN returns a result set that includes all rows in the right table, whether or not they have matching rows from the left table.

How do I join right?

RIGHT JOIN performs a join starting with the second (right-most) table and then any matching first (left-most) table records. RIGHT JOIN and RIGHT OUTER JOIN are the same.

The general syntax is:
  1. SELECT column-names.
  2. FROM table-name1 RIGHT JOIN table-name2.
  3. ON column-name1 = column-name2.
  4. WHERE condition.