WHERE condition before or after join?
7 Answers. 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.
Which is faster join or WHERE?
10 Answers. 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).
When to add condition within join or where?
Agree with 2nd most vote answer that it will make big difference when using LEFT JOIN or RIGHT JOIN. Actually, the two statements below are equivalent. So you can see that AND clause is doing a filter before JOIN while the WHERE clause is doing a filter after JOIN. It is better to add the condition in the Join.
Can a join be filtered in the where clause?
In an SQL query, data can be filtered in the WHERE clause or the ON clause of a join. This guide will examine the difference between the two in PostgreSQL. In order to examine the difference between placing a filter condition in the ON clause and the WHERE clause, two tables have to be created that can be joined together.
When to use cross join or inner join in SQL?
While the CROSS JOIN is useful in certain scenarios, most of the time, you want to join tables based on a specific condition. And, that’s where INNER JOIN comes into play. The SQL INNER JOIN allows us to filter the Cartesian Product of joining two tables based on a condition that is specified via the ON clause.
Do you keep join condition separate from query restriction?
In “SQL Performance Tuning” by Peter Gulutzan and Trudy Pelzer, they tested multiple brands of RDBMS and found no performance difference. I prefer to keep join conditions separate from query restriction conditions.