I am trying to use Lateral Join in Oracle(Oracle Database 11g Release 11.2.0.1.0) but it is giving some error. I have followed this link
https://oracle-base.com/articles/12c/lateral-inline-views-cross-apply-and-outer-apply-joins-12cr1#lateral-inline-views
and applied it on the same data but still it isn't working. Can someone figure out the issue?
SELECT department_name, employee_name
FROM departments d,
LATERAL(SELECT employee_name FROM employees e WHERE e.department_id = d.department_id)
ORDER BY 1, 2;
Adding further details for clarify why I need a lateral join:
I have a table e.g
ID Length
1 20
2 50
3 30
4 40
5 20
6 80
and I want to add another column of the sum of the length of records that have ID less than current row's ID i.e
ID Length Sum
1 20 NULL
2 50 20
3 30 70
4 40 100
5 20 140
6 80 160
With the Lateral JOIN it could have be very simple for example
select A.ID,A.length,Sum from Table A,
Lateral (select sum(B.length) as Sum from Table B where B.id<A.id);
So is there is any alternative to this?
The LATERAL does not work because it is introduced from version 12.
As GMB say.
This is one aproach to the problem you have:
SELECT t1.id, t3.name
FROM test t1
left join (select id, name from test t2) t3
on t1.id = t3.id
order by 2, 1
Here is a DEMO
Or maybe you wanted something like this:
select
t1.id,
t1.name
from test t1
where t1.name in (select t2.name
from test t2
where t2.id = t1.id)
order by 1, 2;
If none of the above approaches does not help you (it is not what you wanted), then there is another way. You can "enable" LATERAl in your old Oracle 11 version like this:
alter session set events '22829 trace name context forever';
You see, this option/feature did existed in older versions but it was not "enabled".
Here is a DEMO showing that your statement on your example data first trhows an error and then after this alter session command, it works.
If you want a query that will give you a resul as in your question and will work on 11g then you can use this:
select ID, Length, LAG(ACUM) OVER (order by ID) sum
from (SELECT ID
, length
, Sum(length) OVER (ORDER BY id) as ACUM
FROM Table1
group by ID, length)
And the same thing can be done in a "more easy" way:
SELECT id,
length,
(SELECT Sum(length)
FROM Table1 b
WHERE a.id > b.id) ACUM
FROM Table1 a
Here is the demo where you can see this query returns the same ersults.
Hope this helps.
Your query is fine, however the LATERAL JOIN syntax was added in Oracle 12.1, so it is not available for 11.2 version, that you are running.
For your use case, you can use a regular join:
SELECT d.department_name, e.employee_name
FROM department d
INNER JOIN employee e ON e.department_id = d.department_id
ORDER BY 1, 2
Related
Assume there is a table name "test" below:
name value
n1 1
n2 2
n3 3
Now, I want to get the name which has the max value, I have some solution below:
Solution 1:
SELECT TOP 1 name
FROM test
ORDER BY value DESC
solution 2:
SELECT name
FROM test
WHERE value = (SELECT MAX(value) FROM test);
Now, I hope use join operation to find the result, like
SELECT name
FROM test
INNER JOIN test ON...
Could someone please help and explain how it works?
If you are looking for JOIN then
SELECT T.name, T.value
FROM test T
INNER JOIN
( SELECT T1.name, T1.value ,
RANK() OVER (PARTITION BY T1.name ORDER BY T1.value) N
FROM test T1
WHERE T1.value IN (SELECT MAX(t2.value) FROM test T2)
)T3 ON T3.N = 1 AND T.name = T3.name
FIDDLE DEMO
or
select name, value
from
(
select name, value,
row_number() over(order by value desc) rn
from test
) src
where rn = 1
FIDDLE DEMO
First, note that solutions 1 and 2 could give different results when value is not unique. If in your test data there would be an additional record ('n4', 3), then solution 1 would return either 'n3' or 'n4', but solution 2 would return both.
A solution with JOIN will need aliases for the table, because as you started of, the engine would say Ambiguous column name 'name'.: it would not know whether to take name from the first or second occurrence of the test table.
Here is a way to complete the JOIN version:
SELECT t1.name
FROM test t1
LEFT JOIN test t2
ON t2.value > t1.value
WHERE t2.value IS NULL;
This query takes each of the records, and checks if any records exist that have a higher value. If not, the first record will be in the result. Note the use of LEFT: this denotes an outer join, so that records from t1 that have no match with t2 -- based on the ON condition -- are not immediately rejected (as would be the case with INNER): in fact, we want to reject all the other records, which is done with the WHERE clause.
A way to understand this mechanism, is to look at a variant of the query above, which lacks the WHERE clause and returns the values of both tables:
SELECT t1.value, t2.value
FROM test t1
LEFT JOIN test t2
ON t2.value > t1.value
On your test data this will return:
t1.value t2.value
1 2
1 3
2 3
3 (null)
Note that the last entry would not be there if the join where an INNER JOIN. But with the outer join, one can now look for the NULL values and actually get those records in the result that would be excluded from an INNER JOIN.
Note that this query will give the same result as solution 2 when there are duplicate values. If you want to have also only one result like with solution 1, it suffices to add TOP 1 after SELECT.
Here is a fiddle.
Alternative with pure INNER JOIN
If you really want an INNER join, then this will do it. Again the TOP 1 is only needed if you have non-unique values:
SELECT TOP 1 t1.name
FROM test t1
INNER JOIN (SELECT Max(value) AS value FROM test) t2
ON t2.value = t1.value;
But this one really is very similar to what you did in solution 2. Here is fiddle for it.
I have a table with 1 record, which then ties back to a secondary table which can contain either no match, 1 match, or 2 matches.
I need to fetch the corresponding records and display them within the same row which would be easy using left join if I just had 1 or no matches to tie back, however, because I can get 2 matches, it produces 2 records.
Example with 1 match:
Select T1.ID, T1.Person1, T2.Owner
From T1
Left Join T2
ON T1.ID = T2.MatchID
Output
ID Person1 Owner1
----------------------
1 John Frank
Example with 2 match:
Select T1.ID, T1.Person1, T2.Owner
From T1
Left Join T2
ON T1.ID = T2.MatchID
Output
ID Person1 Owner
----------------------
1 John Frank
1 John Peter
Is there a way I can formulate my select so that my output would reflect the following When I have 2 matches:
ID Person1 Owner1 Owner2
-------------------------------
1 John Frank Peter
I explored Oracle Pivots a bit, however couldn't find a way to make this work. Also explored the possibility of using left join on the same table twice using MIN() and MAX() when fetching the matches, however I can only see myself resorting this as a "no other option" scenario.
Any suggestions?
** EDIT **
#ughai - Using CTE does address the issue to some extent, however when attempting to retrieve all of the records, the details derived from this common table isn't showing any records on the LEFT JOIN unless I specify the "MatchID" (CASE_MBR_KEY) value, meaning by removing the "where" clause, my outer joins produce no records, even though the CASE_MBR_KEY values are there in the CTE data.
WITH CTE AS
(
SELECT TEMP.BEAS_KEY,
TEMP.CASE_MBR_KEY,
TEMP.FULLNAME,
TEMP.BIRTHDT,
TEMP.LINE1,
TEMP.LINE2,
TEMP.LINE3,
TEMP.CITY,
TEMP.STATE,
TEMP.POSTCD,
ROW_NUMBER()
OVER(ORDER BY TEMP.BEAS_KEY) R
FROM TMP_BEN_ASSIGNEES TEMP
--WHERE TEMP.CASE_MBR_KEY = 4117398
)
The reason for this is because the ROW_NUMBER value, given the amount of records won't necessarily be 1 or 2, so I attempted the following, but getting ORA-01799: a column may not be outer-joined to a subquery
--// BEN ASSIGNEE 1
LEFT JOIN CTE BASS1
ON BASS1.CASE_MBR_KEY = C.CASE_MBR_KEY
AND BASS1.R IN (SELECT min(R) FROM CTE A WHERE A.CASE_MBR_KEY = C.CASE_MBR_KEY)
--// END BA1
--// BEN ASSIGNEE 2
LEFT JOIN CTE BASS2
ON BASS2.CASE_MBR_KEY = C.CASE_MBR_KEY
AND BASS2.R IN (SELECT MAX(R) FROM CTE B WHERE B.CASE_MBR_KEY = C.CASE_MBR_KEY)
--// END BA2
** EDIT 2 **
Fixed the above issue by moving the Row number clause to the "Where" portion of the query instead of within the JOIN clause. Seems to work now.
You can use CTE with ROW_NUMBER() with 2 LEFT JOIN OR with PIVOT like this.
SQL Fiddle
Query with Multiple Left Joins
WITH CTE as
(
SELECT MatchID,Owner,ROW_NUMBER()OVER(ORDER BY Owner) r FROM t2
)
select T1.ID, T1.Person, t2.Owner as Owner1, t3.Owner as Owner2
FROM T1
LEFT JOIN CTE T2
ON T1.ID = T2.MatchID AND T2.r = 1
LEFT JOIN CTE T3
ON T1.id = T3.MatchID AND T3.r = 2;
Query with PIVOT
WITH CTE as
(
SELECT MatchID,Owner,ROW_NUMBER()OVER(ORDER BY Owner) R FROM t2
)
SELECT ID, Person,O1,O2
FROM T1
LEFT JOIN CTE T2
ON T1.ID = T2.MatchID
PIVOT(MAX(Owner) FOR R IN (1 as O1,2 as O2));
Output
ID PERSON OWNER1 OWNER2
1 John Maxwell Peter
If you know there are at most two matches, you can also use aggregation:
Select T1.ID, T1.Person1,
MIN(T2.Owner) as Owner1,
(CASE WHEN MIN(t2.Owner) <> MAX(t2.Owner) THEN MAX(t2.Owner) END) as Owner2
From T1 Left Join
T2
on T1.ID = T2.MatchID
Group By t1.ID, t1.Person1;
I want to Join two tables in sql
e.g.:
Table 1
ID
1
2
3
Table 2
ID SEC
1 Hospital
1 Medical
2 Clinic
2 University
3 College
I want result like
ID SEC
1 Hospital, Medical
2 CLinic, University
3 College
You can use the group_concat aggregate function, which would actually allow you to do this without even joining:
EDIT: Now that the comment explained the question is actually about sqlite and not mysql as it was initially tagged, the syntax is slightly different:
SELECT id, GROUP_CONCAT(SEC, ', ')
FROM table2
GROUP BY id
JOIN and then use GROUP_CONCAT with group by.
select T1.id , GROUP_CONCAT(SEC SEPERATOR ',')
FROM Table1 T1
JOIN Table2 T2
on T1.id = T2.id
GROUP BY T1.id
So I think I've seen a solution to this however they are all very complicated queries. I'm in oracle 11g for reference.
What I have is a simple one to many join which works great however I don't need the many. I just want the left table (the one) to just join any 1 row which meets the join criteria...not many rows.
I need to do this because the query is in a rollup which COUNTS so if I do the normal left join I get 5 rows where I only should be getting 1.
So example data is as follows:
TABLE 1:
-------------
TICKET_ID ASSIGNMENT
5 team1
6 team2
TABLE 2:
-------------
MANAGER_NAME ASSIGNMENT_GROUP USER
joe team1 sally
joe team1 stephen
joe team1 louis
harry team2 ted
harry team2 thelma
what I need to do is join these two tables on ASSIGNMENT=ASSIGNMENT_GROUP but only have 1 row returned.
when I do a left join I get three rows returned beaucse that is the nature of hte left join
If oracle supports row number (partition by) you can create a sub query selecting where row equals 1.
SELECT * FROM table1
LEFT JOIN
(SELECT *
FROM (SELECT *,
ROW_NUMBER()
OVER(PARTITION BY assignmentgroup ORDER BY assignmentgroup) AS Seq
FROM table2) a
WHERE Seq = 1) v
ON assignmet = v.assignmentgroup
You could do something like this.
SELECT t1.ticket_id,
t1.assignment,
t2.manager_name,
t2.user
FROM table1 t1
LEFT OUTER JOIN (SELECT manager_name,
assignment_group,
user,
row_number() over (partition by assignment_group
--order by <<something>>
) rnk
FROM table2) t2
ON ( t1.assignment = t2.assignment_group
AND t2.rnk = 1 )
This partitions the data in table2 by assignment_group and then arbitrarily ranks them to pull one arbitrary row per assignment_group. If you care which row is returned (or if you want to make the row returned deterministic) you could add an ORDER BY clause to the analytic function.
I think what you need is to use GROUP BY on the ASSIGNMENT_GROUP field.
http://www.w3schools.com/sql/sql_groupby.asp
In MySQL you could just GROUP BY ASSIGNMENT and be done. Oracle is more strict and refuses to just choose (in an undefined way) which values of the three rows to choose. That means all returned columns need to be part of GROUP BY or be subject to an aggregat function (COUNT, MIN, MAX...)
You can of course choose to just don't care and use some aggregat function on the returned columns.
select TICKET_ID, ASSIGNMENT, MAX(MANAGER_NAME), MAX(USER)
from T1
left join T2 on T1.ASSIGNMENT=T2.ASSIGNMENT_GROUP
group by TICKET_ID, ASSIGNMENT
If you do that I would seriously doubt that you need the JOIN in the first place.
MySQL could also help with GROUP_CONCAT in the case that you want a string concatenation of group values for a column (humans often like that), but with Oracle that is staggeringly complex.
Using a subquery as already suggested is an option, look here for an example. It also allows you to sort the subquery before selecting the top row.
In Oracle, if you want 1 result, you can use the ROWNUM statement to get the first N values of a query e.g.:
SELECT *
FROM TABLEX
WHERE
ROWNUM = 1 --gets the first value of the result
The problem with this single query is that Oracle never returns the data in the same order. So, you must oder your data before use rownum:
SELECT *
FROM
(SELECT * FROM TABLEX ORDER BY COL1)
WHERE
ROWNUM = 1
For your case, looks like you only need 1 result, so your query should look like:
SELECT *
FROM
TABLE1 T1
LEFT JOIN
(SELECT *
FROM TABLE2 T2 WHERE T1.ASSIGNMENT = T2.ASSIGNMENT_GROUP
AND
ROWNUM = 1) T3 ON T1.ASSIGNMENT = T3.ASSIGNMENT_GROUP
you can use subquery - select top 1
This is my table:
ID KEY VALUE
1 alpha 100
2 alpha 500
3 alpha 22
4 beta 60
5 beta 10
I'm trying to retrieve a list of all KEY-s with their latest values (where ID is in its maximum):
ID KEY VALUE
3 alpha 22
5 beta 10
In MySQL I'm using this query, which is not effective:
SELECT temp.* FROM
(SELECT * FROM t ORDER BY id DESC) AS temp
GROUP BY key
Is it possible to avoid a sub-query in this case?
Use an INNER JOIN to join with your max ID's.
SELECT t.*
FROM t
INNER JOIN (
SELECT ID = MAX(ID)
FROM t
GROUP BY
key
) tm ON tm.ID = t.ID
Assuming the ID column is indexed, this is likely as fast as its going to get.
here is the mysql documentation page that discusses this topic.
it presents three distinct options.
the only one that doesn't involve a sub query is:
SELECT t1.id, t1.k, t1.value
FROM t t1
LEFT JOIN t t2 ON t1.k = t2.k AND t1.id < t2.id
WHERE t2.k IS NULL;
There's page in the manual explaining how to do this