Quick Answer: What Is The Difference Between A Left Join And A Left Outer Join?

Is Outer apply same as LEFT JOIN?

OUTER APPLY resembles LEFT JOIN, but has an ability to join table-evaluated functions with SQL Tables.

OUTER APPLY’s final output contains all records from the left-side table or table-evaluated function, even if they don’t match with the records in the right-side table or table-valued function..

Why would a left join add rows?

You are getting (possible) multiple rows for each row in your left table because there are multiple matches for the join condition. If you want your total results to have the same number of rows as there is in the left part of the query you need to make sure your join conditions cause a 1-to-1 match.

How is the left outer join symbol?

The left outer join is written as R ⟕ S where R and S are relations. The result of the left outer join is the set of all combinations of tuples in R and S that are equal on their common attribute names, in addition (loosely speaking) to tuples in R that have no matching tuples in S.

What does a left outer join do?

A left outer join returns all the values from an inner join plus all values in the left table that do not match to the right table, including rows with NULL (empty) values in the link column.

What is left outer join example?

Suppose, we want to join two tables: A and B. 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.

Is Cross apply faster than inner join?

While most queries which employ CROSS APPLY can be rewritten using an INNER JOIN, CROSS APPLY can yield better execution plan and better performance, since it can limit the set being joined yet before the join occurs.

What is a cross join?

The CROSS JOIN is used to generate a paired combination of each row of the first table with each row of the second table. This join type is also known as cartesian join. … The main idea of the CROSS JOIN is that it returns the Cartesian product of the joined tables.

When to use inner join vs LEFT JOIN?

Generally, we use INNER JOIN when we want to select only rows that match an ON condition. If no rows match the ON condition, then it will not return any results. … We use a LEFT JOIN when we want every row from the first table, regardless of whether there is a matching row from the second table.

Is a left join inner or outer?

Different Types of SQL JOINs Here are the different types of the JOINs in SQL: (INNER) JOIN: Returns records that have matching values in both tables. LEFT (OUTER) JOIN: Returns all records from the left table, and the matched records from the right table.

How does LEFT JOIN work?

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.

Why use outer apply in SQL?

The OUTER APPLY operator returns all the rows from the left table expression irrespective of its match with the right table expression. For those rows for which there are no corresponding matches in the right table expression, it contains NULL values in columns of the right table expression.

Which is faster left or inner 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.

What is the difference between full outer join and outer join?

An Outer join basically differs from the Inner join in how it handles the false match condition. … Right Outer Join: Returns all the rows from the RIGHT table and matching records between both the tables. Full Outer Join: It combines the result of the Left Outer Join and Right Outer Join.

What is outer join with example?

The FULL OUTER JOIN returns a result set that includes rows from both left and right tables. When no matching rows exist for the row in the left table, the columns of the right table will have nulls. Similarly, when no matching rows exist for the row in the right table, the column of the left table will have nulls.