Is there any condition under which the two queries will yield different results?
select * from a,b,c where a.id = b.id(+) and a.id=c.id(+);
select * from a,b,c where a.id = b.id(+) or a.id=c.id(+);
I think in both cases, it will return the row if the id is in table a.
The second select fails with ORA-01719, Outer join operator (+) not allowed in operand of OR or IN.
Yet another reason to use ANSI JOIN syntax. You couldn't even conceive of this question if you were doing so.
Related
i'm having a technical and syntax problem with JOINS in ORACLE.
If i have 7 tables, listed below:
FROM
QT_QTS.PLA_ORDEM_PRODUCAO pla,
qt_qts.res_tubo_austenitizacao aust,
qt_qts.res_tubo_revenimento1 res_rev1,
qt_qts.res_tubo_revenimento2 res_rev2,
limsprod.SAMPLE sp,
limsprod.test t,
limsprod.result r
I need to get ALL the data in the "limsprod.result r" table linked with similar corresponding data inside the qt_qts.res_tubo_austenitizacao aust, qt_qts.res_tubo_revenimento1 res_rev1 and qt_qts.res_tubo_revenimento2 res_rev2 tables.
How can I do this join using Oracle Database? I tried a left join, but it did not work.
It is impossible to answer that question. We have nothing but list of some tables. I'm not sure I'd even want to do that instead of you.
However, here's a suggestion: start with one table:
select * from limsprod.result r;
It'll return all rows. Then join it to another table:
select *
from limsprod.result r join qt_qts.res_tubo_austenitizacao aust on aust.id = r.id
and see what happens - did you get all rows you want? If not, should you add another JOIN condition? Perhaps an outer join? Don't move on to the third table until you sort that out. Once you're satisfied with the result, add another table:
select *
from limsprod.result r join qt_qts.res_tubo_austenitizacao aust on aust.id = r.id
join qt_qts.res_tubo_revenimento1 res_rev1 on res_rev1.idrr = aust.idrr
Repeat what's being said previously.
I want to compare a a value against 2 values without using OR or DECODE. The value I want to compare with two values is the one which I am getting as a return code of a function. If I use OR or DECODE then I have to call function twice and it gives performance hit. Currently I am coding as below
select *
from table1 t1, table2 t1
where t1.empid = t2.empid
and myfunction(t2.balance) = t1.total OR myfunction(t2.balance) = -1
Please suggest if there is a way to call function once and compare with 2 values.
To shorten your code you could use IN operator which acts like OR.
select *
from table1 t1
join table2 t1 on
t1.empid = t2.empid
and myfunction(t2.balance) in (t1.total, -1)
I've also replaced old-fashioned join syntax in where clause for JOIN keyword and you're advised to be using that in your future SQL journeys.
Good thing to know would be that even though you call the function twice, most modern databases would actually call it only once, so I wouldn't be that much concerned about it.
Query 1
select student.identifier,
id_tab.reporter_name,
non_id_tab.reporter_name
from student_table student
inner join id_table id_tab on (student.is_NEW = 'Y'
and student.reporter_id = id_tab.reporter_id
and id_tab.name in('name1','name2'))
inner join id_table non_id_tab on (student.non_reporter_id = non_id_tab.reporter_id)
Query 2
select student.identifier,
id_tab.reporter_name,non_id_tab.reporter_name
from student_table student,
id_table id_tab,
id_table non_id_tab
where student.is_NEW = 'Y'
and student.reporter_id = id_tab.reporter_id
and id_tab.name in('name1','name2')
and student.non_reporter_id = non_id_tab.reporter_id
Since these two queries produce exactly same output,I am assuming they are syntactically same(please correct me if I am wrong).
I was wondering whether either of them is more efficient that the other.
Can anyone help me here please?
I would rewrite it as follows, using the ON only for JOIN conditions and moving the filters to a WHERE condition:
...
from student_table student
inner join id_table id_tab on ( student.reporter_id = id_tab.reporter_id )
inner join id_table non_id_tab on (student.non_reporter_id = non_id_tab.reporter_id)
where student.is_NEW = 'Y'
and id_tab.name in('name1','name2')
This should give a more readable query; however, no matter how you write it (the ANSI join is highly preferrable), you should check the explain plans to understand how the query will be executed.
In terms of performance, there should be no difference.
Execution Plans created by the Oracle optimizer do not differ.
In terms of readability, joining tables inside the WHERE clause is an old style (SQL89).
From SQL92 and higher, it is recommended to use the JOIN syntax.
Can we perform outer join with inquality operators.
When I tried I got the result for right outer join but it's not working for left outer join.
SELECT EMP.ENAME,EMP.SALARY,SALG.SALARY_GRADE
FROM EMPLOYEE EMP , SALARY_GRADES SALG
WHERE EMP.SAL BETWEEN SALG.FROM_RANGE(+) AND SALG.TO_RANGE
Above query is generating the result as inner join where as below query is working fine.
SELECT EMP.ENAME,EMP.SALARY,SALG.SALARY_GRADE
FROM EMPLOYEE EMP , SALARY_GRADES SALG
WHERE EMP.SAL(+) BETWEEN SALG.FROM_RANGE AND SALG.TO_RANGE
I meant to say that right outer join is working fine but not left outer join.
Ummm, yes. Did you create a simple test case to demonstrate? Please always do this.
Both LEFT and RIGHT JOINs work fine. Given the following schema:
create table a (
id number
, val number );
insert all
into a values (1, 1)
into a values (2, 2)
into a values (3, 5)
select * from dual;
create table b (
id number
, min_val number
, max_val number );
insert all
into b values (1, 1, 1)
into b values (2, 1, 6)
into b values (3, 4, 6)
into b values (3, 10, 12)
select * from dual;
These two queries return the expected data. Please note my use of ANSI joins.
select *
from a
left outer join b
on a.val between b.min_val and b.max_val;
select *
from a
right outer join b
on a.val between b.min_val and b.max_val;
Here's the proof.
If you're ever in any doubt as to whether there is a problem with the database or your code you should assume either that your code is incorrect or that the data in your database simply does not exist. It's highly unlikely to be the database itself.
A very good way to test this is to do as I have done, create a very simple example. A short, self-contained, correct example that demonstrates the concepts you're using. You can then apply this to your own code to work out where you might have been going wrong.
You've commented:
Thanks for your answer but......when I insert one more record with 4
as id and 50 as value using insert into a values(4,50); then if i
query using oracle proprietary syntax like select * from a, b where
a.val between b.min_val(+) and b.max_val; I am not getting inserted
record in the result...? It is working with ansi syntax but not with
traditional syntax.....
So, this would imply that your query using the Oracle proprietary syntax is incorrect. I much prefer the ANSI standard as it's extremely obvious if you've done something wrong and it's portable. However, if you want to use the Oracle syntax the reason is that you've turned it into an INNER JOIN but not stating that both items in the BETWEEN are part of the OUTER JOIN:
select *
from a
, b
where a.val between b.min_val(+) and b.max_val(+);
I got the following tables (just an example): vehicles, vehicle_descriptions, vehicle_parts
vehicles have 1 to many with vehicle_descriptions and vehicle_parts. There may not be a corresponding vehicle_description/part for a given vehicle.
SELECT * FROM vehicles
LEFT OUTER JOIN vehicles d ON vehicles.vin = d.vin AND d.summary NOT LIKE 'honda'
LEFT OUTER JOIN
(SELECT SUM(desc_total) FROM vehicle_descriptions WHERE NOT LIKE desc 'honda' GROUP BY vin) b
ON vehicles.vin = vehicle_b.vin
LEFT OUTER JOIN
(SELECT SUM(part_count) FROM vehicle_parts WHERE part_for NOT LIKE 'honda' GROUP BY vin) c ON vehicles.vin = c.vin
If either vehicle_desc, vehicles, or part contains the exclusion term, the whole record should not show up in the result set. The query above will return a record even if one of the tables contain the exclusion term Honda. How would I fix the above query?
You're not using any of the information in either sum() as part of what you show, just to decide whether to include the vehicle. And you're doing an unnecessary self join in your first clause. Generally in situations like this, the "exists" and "not exists" clauses work well. So what about this? I'll use Oracle syntax, you can convert to ANSI of course.
SELECT * FROM vehicles v where summary <> 'honda'
and not exists (select 1 from vehicle_descriptions d where d.vin = v.vin and d.desc <> 'honda')
and not exists (select 1 from vehicle_parts p where p.vin = v.vin and p.part_for <> 'honda')