I am trying to select values from three different tables.
When I select all columns it works well, but if I select specific column, the SQL Error [42000]: JDBC-8027:Column name is ambiguous. appear.
this is the query that selected all that works well
SELECT
*
FROM (SELECT x.*, B.*,C.* , COUNT(*) OVER (PARTITION BY x.POLICY_NO) policy_no_count
FROM YIP.YOUTH_POLICY x
LEFT JOIN
YIP.YOUTH_POLICY_AREA B
ON x.POLICY_NO = B.POLICY_NO
LEFT JOIN
YIP.YOUTH_SMALL_CATEGORY C
ON B.SMALL_CATEGORY_SID = C.SMALL_CATEGORY_SID
ORDER BY x.POLICY_NO);
and this is the error query
SELECT DISTINCT
x.POLICY_NO,
x.POLICY_TITLE,
policy_no_count ,
B.SMALL_CATEGORY_SID,
C.SMALL_CATEGORY_TITLE
FROM (SELECT x.*, B.*,C.* , COUNT(*) OVER (PARTITION BY x.POLICY_NO) policy_no_count
FROM YIP.YOUTH_POLICY x
LEFT JOIN
YIP.YOUTH_POLICY_AREA B
ON x.POLICY_NO = B.POLICY_NO
LEFT JOIN
YIP.YOUTH_SMALL_CATEGORY C
ON B.SMALL_CATEGORY_SID = C.SMALL_CATEGORY_SID
ORDER BY x.POLICY_NO);
I am trying to select if A.POLICY_NO values duplicate rows more than 18, want to change C.SMALL_CATEGORY_TITLE values to "ZZ" and also want to cahge B.SMALL_CATEGORY_SID values to null.
that is why make 2 select in query like this
SELECT DISTINCT
x.POLICY_NO,
CASE WHEN (policy_no_count > 17) THEN 'ZZ' ELSE C.SMALL_CATEGORY_TITLE END AS C.SMALL_CATEGORY_TITLE,
CASE WHEN (policy_no_count > 17) THEN NULL ELSE B.SMALL_CATEGORY_SID END AS B.SMALL_CATEGORY_SID,
x.POLICY_TITLE
FROM (SELECT x.*, B.*,C.* , COUNT(*) OVER (PARTITION BY x.POLICY_NO) policy_no_count
FROM YIP.YOUTH_POLICY x
LEFT JOIN
YIP.YOUTH_POLICY_AREA B
ON x.POLICY_NO = B.POLICY_NO
LEFT JOIN
YIP.YOUTH_SMALL_CATEGORY C
ON B.SMALL_CATEGORY_SID = C.SMALL_CATEGORY_SID
ORDER BY x.POLICY_NO);
If i use that query, I got SQL Error [42000]: JDBC-8006:Missing FROM keyword. ¶at line 3, column 80 of null error..
I know I should solve it step by step. Is there any way to select specific columns?
That's most probably because of SELECT x.*, B.*,C.* - avoid asterisks - explicitly name all columns you need, and then pay attention to possible duplicate column names; if you have them, use column aliases.
For example, if that select (which is in a subquery) evaluates to
select x.id, x.name, b.id, b.name
then outer query doesn't know which id you want as two columns are named id (and also two names), so you'd have to
select x.id as x_id,
x.name as x_name,
b.id as b_id,
b.name as b_name
from ...
and - in outer query - select not just id, but e.g. x_id.
Related
I have a table student_info, it has column "status", status can be P (present), A (absent), S (ill), T ( transfer), L (left).
I am looking for expected output as below.
status count(*)
P 12
S 1
A 2
T 0
L 0
But output is coming like as below:
Status Count(*)
P 12
S 1
A 2
we need rows against status T and L as well with count zero though no record exist in DB.
#mkuligowski's approach is close, but you need an outer join between the CTE providing all of the possible status values, and then you need to count the entries that actually match:
-- CTE to generate all possible status values
with stored_statuses (status) as (
select 'A' from dual
union all select 'L' from dual
union all select 'P' from dual
union all select 'S' from dual
union all select 'T' from dual
)
select ss.status, count(si.status)
from stored_statuses ss
left join student_info si on si.status = ss.status
group by ss.status;
STATUS COUNT(SI.STATUS)
------ ----------------
P 12
A 2
T 0
S 1
L 0
The CTE acts as a dummy table holding the five statuses you want to count. That is then outer joined to your real table - the outer join means the rows from the CTE are still included even if there is no match - and then the rows that are matched in your table are counted. That allows the zero counts to be included.
You could also do this with a collection:
select ss.status, count(si.status)
from (
select column_value as status from table(sys.odcivarchar2list('A','L','P','S','T'))
) ss
left join student_info si on si.status = ss.status
group by ss.status;
It would be preferable to have a physical table which holds those values (and their descriptions); you could also then have a primary/foreign key relationship to enforce the allowed values in your existing table.
If all the status values actually appear in your table, but you have a filter which happens to exclude all rows for some of them, then you could get the list of all (used) values from the table itself instead of hard-coding it.
If your initial query was something like this, with a completely made-up filter:
select si.status, count(*)
from student_info si
where si.some_condition = 'true'
group by si.status;
then you could use a subquery to get all the distinct values from the unfiltered table, outer join from that to the same table, and apply the filter as part of the outer join condition:
select ss.status, count(si.status)
from (
select distinct status from student_info
) ss
left join student_info si on si.status = ss.status
and si.some_condition = 'true'
group by ss.status;
It can't stay as a where clause (at least here, where it's applying to the right-hand-side of the outer join) because that would override the outer join and effectively turn it back into an inner join.
You should store somewhere your statuses (pherhaps in another table). Otherwise, you list them using subquery:
with stored_statuses as (
select 'P' code, 'present' description from dual
union all
select 'A' code, 'absent' description from dual
union all
select 'S' code, 'ill' description from dual
union all
select 'T' code, 'transfer' description from dual
union all
select 'L' code, 'left' description from dual
)
select ss.code, count(*) from student_info si
left join stored_statuses ss on ss.code = si.status
group by ss.code
I have two tables, Table A has an ID and an Event Date and Table B has an ID, a Description and an Event Date.
Not all IDs in Table A appear in Table B and some IDs appear multiple times in Table B with different Descriptions for each event.
The Description in Table B is an attribute that can change over time, the Event date in Table B is the date that a given ID's Description changes from its default value (kept in another table) to the new value.
I want to find the Description in Table B that matches the Event Date in Table A so, for example
Table Sample Data
A1234 would return Green and A4567 would return Null
I can't create tables here so I need to be able to this with a query.
This query will select last description from before the event:
SELECT * FROM (
SELECT tabA.id, tabA.event_date, tabB.description,
ROW_NUMBER() OVER(PARTITION BY tabB.id ORDER BY tabB.event_date DESC) rn
FROM Table_A tabA
LEFT JOIN Table_B tabB ON tabA.id = tabB.id AND tabB.event_date <= tabA.event_date
) WHERE rn = 1
If I understand well your need, this could be a way:
select a.id, description
from tableA A
left join
(select id,
description,
event_date from_date,
lead(event_date) over (partition by id order by event_date) -1 as to_date
from tableB
) B
on (A.id = B.id and a.event_date between b.from_date and b.to_date)
The idea here is to evaluate, for each row in tableB the range of dates for which that row, and its description, is valid; given this, a simple join should do the job.
You can left join tables like:
select a.ID , b1.DESCRIPTION
from TABLE_A a
left join TABLE_B b1 on a.ID = b1.id and a.EVENT_DATE > b1.EVENT_DATE
left join TABLE_B b2 on a.ID = b2.id and b1.EVENT_DATE < b2.EVENT_DATE and a.EVENT_DATE > b2.EVENT_DATE
where b1.id is null or b2.EVENT_DATE is null;
I need help with my SQL Query I have Two tables that i need to join using a LEFT OUTER JOIN, then i need to create a database view over that particular view. If i run a query on the join to look for name A i need to get that A's latest brand "AP".
Table 1
ID name address
-----------------------
1 A ATL
2 B ATL
TABLE 2
ID PER_ID brand DATEE
--------------------------------------------
1 1 MS 5/19/17:1:00pm
2 1 XB 5/19/17:1:05pm
3 1 AP 5/19/17:2:00pm
4 2 RO 5/19/17:3:00pm
5 2 WE 5/19/17:4:00pm
I tried query a which returns correct result but i get problem 1 when i try to build the database view on top of the join. I tried query b but when i query my view in oracle sql developer i still get all the results but not the latest.
query a:
SELECT * from table_1
left outer join table_2 on table_1.ID = Table_2.PER_ID
AND table_2.DATE = (SELECT MAX(DATE) from table_2 z where z.PER_ID = table_2.PER_ID)
Problem 1
Error report -
ORA-01799: a column may not be outer-joined to a subquery
01799. 00000 - "a column may not be outer-joined to a subquery"
*Cause: <expression>(+) <relop> (<subquery>) is not allowed.
*Action: Either remove the (+) or make a view out of the subquery.
In V6 and before, the (+) was just ignored in this case.
Query 2:
SELECT * from table_1
left outer join(SELECT PER_ID,brand, max(DATEE) from table_2 group by brand,PER_ID) t2 on table_1.ID = t2.PER_ID
Use row_number():
select t1.id, t1.name, t1.address, t2.id as t2_id, t2.brand, t2.datee
from table_1 t1 left outer join
(select t2.*,
row_number() over (partition by per_id order by date desc) as seqnum
from table_2 t2
) t2
on t1.ID = t2.PER_ID and t2.seqnum = 1;
When defining a view, you should be in the habit of listing the columns explicitly.
I'm trying to build a query in Toad Data Point. I have a subquery that has a row number to identify the records I'm interested in. This subquery needs to be left joined onto the main table only when the row number is 1. Here's the query I'm trying to visualize:
SELECT distinct E.EMPLID, E.ACAD_CAREER
FROM PS_STDNT_ENRL E
LEFT JOIN (
SELECT ACAD_CAREER, ROW_NUMBER() OVER (PARTITION BY ACAD_CAREER ORDER BY EFFDT DESC) as RN
FROM PS_ACAD_CAR_TBL
) T on T.ACAD_CAREER = E.ACAD_CAREER and RN = 1
When I try to replicate this, the row number condition is placed in the global WHERE clause. This is not the intended functionality because it removes any records that don't have a match in the subquery effectively making it an inner join.
Here is the query it's generating:
SELECT DISTINCT E.EMPLID, E.ACAD_CAREER, T.RN
FROM SYSADM.PS_STDNT_ENRL E
LEFT OUTER JOIN
(SELECT PS_ACAD_CAR_TBL.ACAD_CAREER,
ROW_NUMBER ()
OVER (PARTITION BY ACAD_CAREER ORDER BY EFFDT DESC)
AS RN
FROM SYSADM.PS_ACAD_CAR_TBL PS_ACAD_CAR_TBL) T
ON (E.ACAD_CAREER = T.ACAD_CAREER)
WHERE (T.RN = 1)
Is there a way to get the query builder to place that row number condition on the left join instead of the global WHERE clause?
I found a way to get this to work.
Add a calculated field to the main table with a value of 1.
Join the row number to this new calculated field.
Now the query has the filter in the join condition instead of the WHERE clause so that it joins as intended. Here is the query it made:
SELECT DISTINCT E.EMPLID, E.ACAD_CAREER, T.RN
FROM SYSADM.PS_STDNT_ENRL E
LEFT OUTER JOIN
(SELECT PS_ACAD_CAR_TBL.ACAD_CAREER,
ROW_NUMBER ()
OVER (PARTITION BY ACAD_CAREER ORDER BY EFFDT DESC)
AS RN
FROM SYSADM.PS_ACAD_CAR_TBL PS_ACAD_CAR_TBL) T
ON (E.ACAD_CAREER = T.ACAD_CAREER) AND (1 = T.RN)
Lets say we have two tables
TableA (A1,A2) , TableB(B1,B2)
Is there any difference (in therms of performance, memory usage ) between the two queries (only order by clause positions are different) below in oracle
Select Y.*, ROWNUM rNum FROM (
select * from
TableA a join TableB b on a.A1 = b.B1
Where a.A2 = 'SomeVal'
Order by b.B2
) A
Select Y.*, ROWNUM rNum FROM (
select * from
TableA a join TableB b on a.A1 = b.B1
Where a.A2 = 'SomeVal'
) A
Order by B2
Yes -- in the latter the rownum is assigned prior to the rows being ordered, and in the former the rownum is assigned after the rows are ordered.
So the first query's rownums might read as, "1,2,3,4,5 ...", whereas the second query's rownums might read, "33,3,5,45,1 ..."