When you use left outer join and right outer join?
Left Outer Join: Returns all the rows from the LEFT table and matching records between both the tables. 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.
WHERE to use left join and WHERE to use right join?
The main difference between these joins is the inclusion of non-matched rows. The LEFT JOIN includes all records from the left side and matched rows from the right table, whereas RIGHT JOIN returns all rows from the right side and unmatched rows from the left table.
Can you add a WHERE clause to a join?
Always put the join conditions in the ON clause if you are doing an INNER JOIN . So, do not add any WHERE conditions to the ON clause, put them in the WHERE clause. If you are doing a LEFT JOIN , add any WHERE conditions to the ON clause for the table in the right side of the join.
Does WHERE come after inner join?
The where clause will be executed before the join so that it doesn’t join unnecessary records. So your code is fine the way it is.
What is the difference between having and where clause?
A HAVING clause is like a WHERE clause, but applies only to groups as a whole (that is, to the rows in the result set representing groups), whereas the WHERE clause applies to individual rows. A query can contain both a WHERE clause and a HAVING clause.
When to use left join and right join in SQL?
LEFT (OUTER) JOIN : Returns all records from the left table, and the matched records from the right table. 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 table.
What is a WHERE clause?
A WHERE clause defines conditions that you want to apply to a query. In a non-aggregate query, WHERE clauses are used instead of HAVING clauses. In an aggregate query, a WHERE clause defines conditions that you want to apply before any calculations are performed.
Is inner join faster than where clause?
Which is faster inner join or where clause? Theoretically, no, it shouldn’t be any faster. The query optimizer should be able to generate an identical execution plan. However, some database engines can produce better execution plans for one of them (not likely to happen for such a simple query but for complex enough ones).
What is difference between JOIN, INNER JOIN and where clause?
INNER JOIN: Values matched in both tables are returned.
Why did my where clause affect my left join?
There are times when I review SQL queries and find people using LEFT OUTER JOINs but then use WHERE clauses that turn those joins into INNER JOINs. Recently as I mentioned this to someone they reminded me that I should blog about it…so here I am blogging about it.
How to use LEFT OUTER JOIN?
PySpark DataFrame Left Outer Join Example. Below is an example of how to use Left Outer Join ( left,leftouter,left_outer) on PySpark DataFrame.