Technically, it returns the result set of a query without WHERE-Clause. As per SQL concern and advancement, there are 3-types of joins and all RDBMS joins can be achieved using these types of …

Dec 22, 2012 · SELECT A.Colour, B.Colour FROM A LEFT OUTER JOIN B ON A.Colour = B.Colour SQL Fiddle Outer Joins are logically evaluated in the same way as inner joins except that if a row …

FULL JOIN: combines the results of both left and right outer joins. The joined table will contain all records from both the tables and fill in NULLs for missing matches on either side. SELF JOIN: joins a …

Dec 27, 2018 · Inner joins only return a row where there is a match on the join condition, whereas, a LEFT OUTER join returns the same rows returned by an INNER join, as well as a ROW for any rows …

Nov 1, 2013 · Instead of one join with OR it turned into three joins. With each condition in a seprate join and a final join to get that one matching row from either first or second join.

Taken from the Reference Manual (14.2.10.11 Rewriting Subqueries as Joins): A LEFT [OUTER] JOIN can be faster than an equivalent subquery because the server might be able to optimize it better—a …

Is there any efficiency difference in an explicit vs implicit inner join? For example: SELECT * FROM table a INNER JOIN table b ON a.id = b.id; vs. SELECT a.*, b.* FROM table a, table b WHERE a.i...

The question and solutions pertain specifically to INNER JOINs. If the join is a LEFT/RIGHT/FULL OUTER JOIN, then it is not a matter of preference or performance, but one of correct results. The …

Sep 2, 2008 · Inner joins (or what is the default when using only "join") is a join where only the elements that match the criteria are present on both tables. The "outer" joins are the same as the inner join …

"joins" is the killer for performance, the bigger your data is, the more pain you will feel; Try to get rid of joins, not try to improve query performance by keeping joins unless you have to.