What does full join do in SQL?
The FULL OUTER JOIN keyword returns all records when there is a match in left (table1) or right (table2) table records. Tip: FULL OUTER JOIN and FULL JOIN are the same.
What is the meaning of full join?
A FULL JOIN returns all the rows from the joined tables, whether they are matched or not i.e. you can say a full join combines the functions of a LEFT JOIN and a RIGHT JOIN . Full join is a type of outer join that’s why it is also referred as full outer join. The following Venn diagram illustrates how full join works.
What is SQL full outer join?
In SQL the FULL OUTER JOIN combines the results of both left and right outer joins and returns all (matched or unmatched) rows from the tables on both sides of the join clause.
Is full join an outer join?
Full Outer Join returns all the rows from both the table. When no matching rows exist for the row in the left table, the columns of the right table are null padded. Full outer join is the union of left outer join and right outer join.
Is full join same as cross join?
For SQL Server, CROSS JOIN and FULL OUTER JOIN are different. CROSS JOIN is simply Cartesian Product of two tables, irrespective of any filter criteria or any condition. FULL OUTER JOIN gives unique result set of LEFT OUTER JOIN and RIGHT OUTER JOIN of two tables. It also needs ON clause to map two columns of tables.
How do you do a Cartesian join in SQL?
In SQL Server, the cartesian product is really a cross-join which returns all the rows in all the tables listed in a query: each row in the first table is paired with all the rows in the second table. This happens when there is no relationship defined between the two tables.
What is difference between inner join and outer join?
The major difference between inner and outer joins is that inner joins result in the intersection of two tables, whereas outer joins result in the union of two tables.
What is difference between inner join and full join?
Inner join returns only the matching rows between both the tables, non-matching rows are eliminated. Full Join or Full Outer Join returns all rows from both the tables (left & right tables), including non-matching rows from both the tables.
IS LEFT join faster than 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.
Is inner join expensive?
The reason why joins are typically expensive is that joining may result in a number of tuples larger than the size of either table. However, sometimes the join attributes in one table functionally determine a unique tuple in another table.