Difference between left inner join and left outer join

Difference between Left Join and Left Outer Join. The join can either be an inner join or an outer join. An inner join returns records which have matches in both tables as opposed to an outer join which is the opposite of the inner. The outer join therefore returns those records that do not have matches in either table.

An outer join returns a set of records (or rows) that include what an inner join would return but also includes other rows for which no corresponding match is found in the other table. Left join will return all the rows from the left table and matching rows from right table.

In case of no match with right side table it will return NULL value. Left Join ” and “Left Outer Join ” are used interchangeably because records which are returned will be the same with either of these. ID means show only records where the same ID value exists in both tables. INNER JOIN : returns rows when there is a match in both tables. 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. FULL JOIN : It combines the of both left. What is the difference between Left, Right,.

The OUTER join is also called FULL OUTER as opposed to LEFT and RIGHT joins that are PARTIAL of the OUTER join.

Joins are performed based on something called a predicate, which specifies the condition to use in order to perform a join. The difference between an inner join and an outer join is that an inner join will return only the rows that actually match based on the join predicate. The basic difference between the Inner Join and Outer Join is that inner join compares and combine only the matching tuples from bothe the tables. On the other hands, the Outer Join compare and combines all the tuples from both the tables being compared.

The database size of the resultant obtained from the Inner Join is smaller that Outer Join. Joins come in three main groups – inner join, cross join and outer join. A left outer join displays all the rows from the left of the table. A right join displays all rows from the right of the table. Alternating the SQL sequence can eliminate use of both right and left outer joins and instead use only one.

Left Join” and “Left Outer Join” are used interchangeably because records which are returned will be the same with either of these. Full Outer Join is the combination of both, Left Outer Join and Right Outer Join. Initially, it applies inner join on Table_A and Table_B to retrieve matching tuples from both the tables.

Then it extends those tuples of Table_A with NULL that do not have a matching tuple in Table_B. Left outer join returns all rows of table on left side of join. The rows for which there is no matching row on right side, result contains NULL in the right side.

There is actually no difference between a left join and a left outer join – they both refer to the exact same operation in SQL. An example will help clear this up. Though both inner and outer joins include rows from both tables when the match condition is successful, they differ in how they handle a false match condition.

This is all the recordsfrom the left tables and the matching records from the right table.

Where as RIGHT OUTER JOIN returns all records from the RIGHT table irrespective of whether there are any matching rows in the LEFT table. LEFT OUTER JOIN will get you the same as the regular LEFT JOIN.