Inner Join vs. Outer Join

Here are the different types of the JOINs in SQL: (INNER) JOIN : Returns records that have matching values in both tables. ... RIGHT (OUTER) JOIN : Returns all records from the right table, and the matched records from the left table. FULL (OUTER) JOIN : Returns all records when there is a match in either left or right ...

1. What is the difference between inner join and outer join?
2. What is faster inner join or outer join?
3. IS LEFT JOIN inner or outer?
4. Why use inner join?
5. What is a natural join?
6. Can we use inner join and for all entries together?
7. Which join is faster in Hana?
8. Which join is faster in MySQL?
9. Which join is better in SQL?
10. IS LEFT JOIN faster than inner join?
11. Why use LEFT JOIN instead of inner join?
12. Is there a difference between left join and left outer join?

What is the difference between inner join and outer join?

Joins in SQL are used to combine the contents of different tables. ... 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 faster inner join or outer join?

9 Answers. 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 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 inner join?

Note: The INNER JOIN keyword selects all rows from both tables as long as there is a match between the columns. If there are records in the "Orders" table that do not have matches in "Customers", these orders will not be shown!

What is a natural join?

A NATURAL JOIN is a JOIN operation that creates an implicit join clause for you based on the common columns in the two tables being joined. Common columns are columns that have the same name in both tables. A NATURAL JOIN can be an INNER join, a LEFT OUTER join, or a RIGHT OUTER join.

Can we use inner join and for all entries together?

The Inner join can be very performant when you use combined table like vbak/vbap/vbep or ekko/ekpo/eket or mara/marc/mard, ... The for all entries statement will be less performant if you have a lot of records ( and don't forget, you have in most cases to delete duplicates, so ... )

Which join is faster in Hana?

From performance point of view, the Left outer join is always faster than Inner join. Inner join is usually slower due to the fact that the join is always executed.

Which join is faster in MySQL?

A LEFT JOIN is not faster than INNER JOIN . It always depends on the structure of your table whereas the proper key index is applied to that or not. If there you do not use a Dependency Or Index Undoubtedly the Left Join is way faster because that not Scan Complete table.

Which join is better in SQL?

There is not a "better" or a "worse" join type. They have different meaning and they must be used depending on it. In your case, you probably do not have employees with no work_log (no rows in that table), so LEFT JOIN and JOIN will be equivalent in results. ... In MySQL CROSS JOIN , INNER JOIN and JOIN are the same.

IS LEFT JOIN faster than inner join?

2 Answers. The Left join seems to be faster because SQL is forced to do the smaller select first and then join to this smaller set of records. For some reason the optimiser doesn't want to do this naturally. Select the first subset of data into a temporary table (or table variable) then join on it.

Why use LEFT JOIN instead of inner join?

You'll use INNER JOIN when you want to return only records having pair on both sides, and you'll use LEFT JOIN when you need all records from the “left” table, no matter if they have pair in the “right” table or not.

Is there a difference between left join and left outer join?

There really is no difference between a LEFT JOIN and a LEFT OUTER JOIN. Both versions of the syntax will produce the exact same result in PL/SQL. Some people do recommend including outer in a LEFT JOIN clause so it's clear that you're creating an outer join, but that's entirely optional.