This question already has answers here:
Difference between JOIN and INNER JOIN
(6 answers)
Closed 8 years ago.
Is there any performance - difference between inner join and simple join?
i.e. does either of them have a better execution plan and/or execution time?
And will both these approaches always yield same result sets?
JOIN with no qualifier is just an abbreviation for INNER JOIN, they are exactly the same. If any database had a performance difference, I would report it as a bug.
Related
This question already has answers here:
LEFT JOIN vs. LEFT OUTER JOIN in SQL Server
(12 answers)
Closed 5 years ago.
LEFT JOIN and LEFT OUTER JOIN works exactly the same way.
Which means the keyword OUTER has no effect or it is optional.
Why do we include a keyword which has no effect in execution?
It is optional, I always assumed that it was originally there as its more descriptive.
However it doesn't actually mean anything as a join is either inner, left, right or full - so the outer key word can be inferred to be relevant for all but inner joins.
This question already has answers here:
Explicit vs implicit SQL joins
(12 answers)
Closed 5 years ago.
I get the same result in both queries below and same execution plan, any difference? or it is just how I prefer to write my query?
SELECT PS.StepID,PR.ProgramID FROM ProgramSteps PS, Programs PR
WHERE PS.ProgramID = PR.ProgramID
SELECT PS.StepID,PR.ProgramID FROM ProgramSteps PS
INNER JOIN Programs PR ON PS.ProgramID = PR.ProgramID
One difference is that the first option hides the intent by expressing the join condition in the where clause.
The second option, where the join condition is written out is more clear for the user reading the query. It shows the exact intent of the query.
As far as performance or any other difference, there shouldn't be any. Both queries should return the exact same result and perform the same under most RDBMS.
And as #Tim Biegeleisen says in the comments:
the comma version is deprecated as of the ANSI-92 SQL standard
This question already has answers here:
Difference between Oracle's plus (+) notation and ansi JOIN notation?
(8 answers)
Closed 9 years ago.
I'm going through some code and came across a view and was wondering what part of the WHERE statement was doing, it looks like so.
receipt_note.receipt_num(+) = receipt_data.receipt_num
receipt_num is a NUMBER in the table. I just don't know what the (+) would be doing here. Is it adding 1 to that number, like in coding where you would do variable++
(+) is the (old) outer join operator in Oracle. It is specifying an outer join between the receipt_num columns of the receipt_note table and the receipt_data table.
This syntax is obsolete; new queries should use OUTER JOIN instead since it is more readable.
This question already has answers here:
INNER JOIN ON vs WHERE clause
(12 answers)
Closed 9 years ago.
imagine I have 2 simple tables
users (id,username,password)
shopping(user_id,product_id)
and I use inner join to find each username buys which product :
select username,product_id
from shopping
inner join users
on users.id=shopping.user_id
but I can write a more simple query without using inner join and it works
select username,product_id
from shopping,users
where shopping.user_id=users.id
and result is the same
I wonder to know what's the advantage of using inner join !!
Inner Join is Used to Extract the Data's from one or more tables, that's why we are going for inner join instead of Where condition
SQL statements are synonymous, though specifying the INNER JOIN is the preferred method and follows ISO format. I prefer it as well because it limits the plumbing of joining the tables from your where clause and makes the goal of your query clearer.
This question already has answers here:
Inner join vs Where
(19 answers)
SQL JOIN - WHERE clause vs. ON clause
(22 answers)
INNER JOIN ON vs WHERE clause
(12 answers)
Closed 9 years ago.
When doing an SQL query,
is there any significant (or any at all) difference in performance between 'WHERE' and 'ON'?
I know there is a significant difference in the resulting set between the two for a LEFT or RIGHT JOIN.
What about an INNER JOIN?
Is there any drawback to using 'ON' for each of my selects rather than 'WHERE' at the end?
Performance wise, they should be the same. However, see this article for an opinion of an industry veteran regarding the readability and maintenace-friendliness.
While the old-style joins still work, you can't do an outer join anymore
Execution plans for both are identical. Many people prefer the use of ON though.