I am trying to use a query to return the count from rows such that the date of the rows matches the maximum date for that column in the table.
Oracle SQL: version 11.2:
The following syntax would seem to be correct (to me), and it compiles and runs. However, instead of returning JUST the count for the maximum, it returns several counts more or less like the "HAIVNG" clause wasn't there.
Select ourDate, Count(1) as OUR_COUNT
from schema1.table1
group by ourDate
HAVING ourDate = max(ourDate) ;
How can this be fixed, please?
You can use:
SELECT MAX(ourDate) AS ourDate,
COUNT(*) KEEP (DENSE_RANK LAST ORDER BY ourDate) AS ourCount
FROM schema1.table1
or:
SELECT ourDate,
COUNT(*) AS our_count
FROM (
SELECT ourDate,
RANK() OVER (ORDER BY ourDate DESC) AS rnk
FROM schema1.table1
)
WHERE rnk = 1
GROUP BY ourDate
Which, for the sample data:
CREATE TABLE table1 (ourDate) AS
SELECT SYSDATE FROM DUAL CONNECT BY LEVEL <= 5 UNION ALL
SELECT SYSDATE - 1 FROM DUAL;
Both output:
OURDATE
OUR_COUNT
2022-06-28 13:35:01
5
db<>fiddle here
I don't know if I understand what you want. Try this:
Select x.ourDate, Count(1) as OUR_COUNT
from schema1.table1 x
where x.ourDate = (select max(y.ourDate) from schema1.table1 y)
group by x.ourDate
One option is to use a subquery which fetches maximum date:
select ourdate, count(*)
from table1
where ourdate = (select max(ourdate)
from table1)
group by ourdate;
Or, a more modern approach (if your database version supports it; 11g doesn't, though):
select ourdate, count(*)
from table1
group by ourdate
order by ourdate desc
fetch first 1 rows only;
You can use this SQL query:
select MAX(ourDate),COUNT(1) as OUR_COUNT
from schema1.table1
where ourDate = (select MAX(ourDate) from schema1.table1)
group by ourDate;
Related
I have this query where a user defined function is added in the select and group by statement.
The inner select query without the WITH clause runs fine and doesn't give any error. But after adding WITH clause it gives the following error -
ORA-00979: not a GROUP BY expression
00979. 00000 - "not a GROUP BY expression"
*Cause:
*Action: Error at Line: 3 Column: 29
I need the WITH clause to return only a subset of the entire result set based on input ranges.
Query is as follows:
WITH INFO AS (
SELECT
GET_EVAULATED_VALUE(T.C_IMP, T.IMP) AS IMPORTANCE,
count(*) AS NO_OF_PC_AFFECTED
FROM TABLE_NAME T
WHERE T.ACNT_REL_ID = 16
GROUP BY
(GET_EVAULATED_VALUE(T.C_IMP, T.IMP))
ORDER BY IMPORTANCE desc
)
SELECT * FROM
(
SELECT ROWNUM AS RN,
(SELECT COUNT(*) FROM INFO) COUNTS,
IMPORTANCE
FROM INFO
)
WHERE RN > 0 AND RN <= 10;
I am not sure how to use CTE with group by on user defined function. But I realized that I can rewrite the query to remove sub-query and CTE and make it simpler as following (and it works):
select * from (
select a.*, ROWNUM rnum from
(SELECT
count(*) over() as COUNTS,
GET_EVAULATED_VALUE(T.C_IMP, T.IMP) AS IMPORTANCE,
count(*) AS NO_OF_PC_AFFECTED
FROM TABLE_NAME T
WHERE T.ACNT_RELATION_ID = 16
GROUP BY
(GET_EVAULATED_VALUE(T.C_IMP, T.IMP))
ORDER BY importance desc) a
where ROWNUM <= 10 )
where rnum >= 0;
Same issue here, I created a table "TABLE_CTE" instead of using a CTE and it worked.
CREATE TABLE TABLE_CTE
AS
SELECT
USER_DEFINED_FUNCTION(date_1),
COUNT(*)
FROM
TABLE_NAME
GROUP BY
USER_DEFINED_FUNCTION(date_1)
;
SELECT * FROM TABLE_CTE
I have a function, which will get greatest of three dates from the table.
create or replace FUNCTION fn_max_date_val(
pi_user_id IN number)
RETURN DATE
IS
l_modified_dt DATE;
l_mod1_dt DATE;
l_mod2_dt DATE;
ret_user_id DATE;
BEGIN
SELECT MAX(last_modified_dt)
INTO l_modified_dt
FROM table1
WHERE id = pi_user_id;
-- this table contains a million records
SELECT nvl(MAX(last_modified_ts),sysdate-90)
INTO l_mod1_dt
FROM table2
WHERE table2_id=pi_user_id;
-- this table contains clob data, 800 000 records, the table 3 does not have user_id and has to fetched from table 2, as shown below
SELECT nvl(MAX(last_modified_dt),sysdate-90)
INTO l_mod2_dt
FROM table3
WHERE table2_id IN
(SELECT id FROM table2 WHERE table2_id=pi_user_id
);
execute immediate 'select greatest('''||l_modified_dt||''','''||l_mod1_dt||''','''||l_mod2_dt||''') from dual' into ret_user_id;
RETURN ret_user_id;
EXCEPTION
WHEN OTHERS THEN
return SYSDATE;
END;
this function works perfectly fine and executes within a second.
-- random user_id , just to test the functionality
SELECT fn_max_date_val(100) as max_date FROM DUAL
MAX_DATE
--------
27-02-14
For reference purpose i have used the table name as table1,table2 and table3 but my business case is similar to what i stated below.
I need to get the details of the table1 along with the highest modified date among the three tables.
I did something like this.
SELECT a.id,a.name,a.value,fn_max_date_val(id) as max_date
FROM table1 a where status_id ='Active';
The above query execute perfectly fine and got result in millisecods. But the problem came when i tried to use order by.
SELECT a.id,a.name,a.value,a.status_id,last_modified_dt,fn_max_date_val(id) as max_date
FROM table1 where status_id ='Active' a
order by status_id desc,last_modified_dt desc ;
-- It took almost 300 seconds to complete
I tried using index also all the values of the status_id and last_modified, but no luck. Can this be done in a right way?
How about if your query is like this?
select a.*, fn_max_date_val(id) as max_date
from
(SELECT a.id,a.name,a.value,a.status_id,last_modified_dt
FROM table1 where status_id ='Active' a
order by status_id desc,last_modified_dt desc) a;
What if you don't use the function and do something like this:
SELECT a.id,a.name,a.value,a.status_id,last_modified_dt x.max_date
FROM table1 a
(
select max(max_date) as max_date
from (
SELECT MAX(last_modified_dt) as max_date
FROM table1 t1
WHERE t1.id = a.id
union
SELECT nvl(MAX(last_modified_ts),sysdate-90) as max_date
FROM table2 t2
WHERE t2.table2_id=a.id
...
) y
) x
where a.status_id ='Active'
order by status_id desc,last_modified_dt desc;
Syntax might contain errors, but something like that + the third table in the derived table too.
I'm trying to adapt a query that works in MSSQL to Oracle, the query is much bigger (this part is just a field from a much bigger query) but I managed to reduce it so it looks simpler.
SELECT CASE WHEN COUNT(*) > 0 THEN COUNT(*)
ELSE (SELECT COUNT(*) FROM table2)
END
FROM table1
The error I'm getting is:
ora-00937 not a single-group group function
Can someone tell me where's the problem or how can I redefine it?
You can try with this query:
SELECT CASE WHEN (SELECT COUNT(*) FROM table1) > 0 then (SELECT COUNT(*) FROM table1)
ELSE (SELECT COUNT(*) FROM table2)
END
FROM dual;
It is still ugly but it works :)
Update:
To explain how it's working:
We have 2 cases:
If there are records in the table1 then show me how many records
there are
If the table1 is empty, then give me the number of records from the
table2
Dual is the dummy table.
I think that NikNik answer is cleaner but another solution would be:
SELECT *
FROM (SELECT CASE
WHEN Count(*) > 0 THEN Count(*)
ELSE (SELECT Count(*)
FROM table2)
END
FROM table1
GROUP BY table1.primarykey1,
table1.primarykey2)
WHERE ROWNUM = 1
It seems that I haven't been clear enough.
The query that seems to work is:
Select ((Select count (table1.id) from table1 where table1.code=2 and table1.name=5) as ‘name5’,
(Select count (table1.id) from table1 where table1.code=2 and table1.name=7) as ‘name7’)
From table.1;
union
Select ((Select count (table1.id) from table1 where table1.code=5 and table1.name=5) as ‘name5’,
(Select count (table1.id) from table1 where table1.code=5 and table1.name=7) as ‘name7’)
From table.1;
union
Select ((Select count (table1.id) from table1 where table1.code=15 and table1.name=5) as ‘name5’,
(Select count (table1.id) from table1 where table1.code=15 and table1.name=7) as ‘name7’)
From table.1;
….
Which gets an outcome like this:
name5 name7
52 47
42 84
61 11
My problem is that the table1.code has a thousand and more values other than 2,5 and 15 and I can not repeat a union statement for so many times.
Well it seems like you actually just want to group by the values in the code column, and you can use IN or EXISTS
select count(table1.id) as theCount, table1.code as theCode
from table1 where table1.code in ('code a','code b', 'etc...')
group by table1.code;
the output would be
theCount||theCode
code a || 8074
code b || 34
etc... || 9575
or something like that but with non notional numbers for counts
HTH
You could try to list all values in a nested select listing integers from a to your value, e.g. 100, like that:
select count table1.id from table1 one where table1.code in (
select rownum from all_objects where rownum < 100
);
or if you don't want to start at "1":
select count table1.id from table1 one where table1.code in (
select rownum n from dual connect by level 10 where n>3
);
Here is my query,
SELECT ID As Col1,
(
SELECT VID FROM TABLE2 t
WHERE (a.ID=t.ID or a.ID=t.ID2)
AND t.STARTDTE =
(
SELECT MAX(tt.STARTDTE)
FROM TABLE2 tt
WHERE (a.ID=tt.ID or a.ID=tt.ID2) AND tt.STARTDTE < SYSDATE
)
) As Col2
FROM TABLE1 a
Table1 has 48850 records and Table2 has 15944098 records.
I have separate indexes in TABLE2 on ID,ID & STARTDTE, STARTDTE, ID, ID2 & STARTDTE.
The query is still too slow. How can this be improved? Please help.
I'm guessing that the OR in inner queries is messing up with the optimizer's ability to use indexes. Also I wouldn't recommend a solution that would scan all of TABLE2 given its size.
This is why in this case I would suggest using a function that will efficiently retrieve the information you are looking for (2 index scan per call):
CREATE OR REPLACE FUNCTION getvid(p_id table1.id%TYPE)
RETURN table2.vid%TYPE IS
l_result table2.vid%TYPE;
BEGIN
SELECT vid
INTO l_result
FROM (SELECT vid, startdte
FROM (SELECT vid, startdte
FROM table2 t
WHERE t.id = p_id
AND t.startdte < SYSDATE
ORDER BY t.startdte DESC)
WHERE rownum = 1
UNION ALL
SELECT vid, startdte
FROM (SELECT vid, startdte
FROM table2 t
WHERE t.id2 = p_id
AND t.startdte < SYSDATE
ORDER BY t.startdte DESC)
WHERE rownum = 1
ORDER BY startdte DESC)
WHERE rownum = 1;
RETURN l_result;
END;
Your SQL would become:
SELECT ID As Col1,
getvid(a.id) vid
FROM TABLE1 a
Make sure you have indexes on both table2(id, startdte DESC) and table2(id2, startdte DESC). The order of the index is very important.
Possibly try the following, though untested.
WITH max_times AS
(SELECT a.ID, MAX(t.STARTDTE) AS Startdte
FROM TABLE1 a, TABLE2 t
WHERE (a.ID=t.ID OR a.ID=t.ID2)
AND t.STARTDTE < SYSDATE
GROUP BY a.ID)
SELECT b.ID As Col1, tt.VID
FROM TABLE1 b
LEFT OUTER JOIN max_times mt
ON (b.ID = mt.ID)
LEFT OUTER JOIN TABLE2 tt
ON ((mt.ID=tt.ID OR mt.ID=tt.ID2)
AND mt.startdte = tt.startdte)
You can look at analytic functions to avoid having to hit the second table twice. Something like this might work:
SELECT id AS col1, vid
FROM (
SELECT t1.id, t2.vid, RANK() OVER (PARTITION BY t1.id ORDER BY
CASE WHEN t2.startdte < TRUNC(SYSDATE) THEN t2.startdte ELSE null END
NULLS LAST) AS rn
FROM table1 t1
JOIN table2 t2 ON t2.id IN (t1.ID, t1.ID2)
)
WHERE rn = 1;
The inner select gets the id and vid values from the two tables with a simple join on id or id2. The rank function calculates a ranking for each matching row in the second table based on the startdte. It's complicated a bit by you wanting to filter on that date, so I've used a case to effectively ignore any dates today or later by changing the evaluated value to null, and in this instance that means the order by in the over clause needs nulls last so they're ignored.
I'd suggest you run the inner select on its own first - maybe with just a couple of id values for brevity - to see what its doing, and what ranks are being allocated.
The outer query is then just picking the top-ranked result for each id.
You may still get duplicates though; if table2 has more than one row for an id with the same startdte they'll get the same rank, but then you may have had that situation before. You may need to add more fields to the order by to break ties in a way that makes sens to you.
But this is largely speculation without being able to see where your existing query is actually slow.