Is there an alternative to re-write the below oracle query without using sub-queries
SELECT COL1,COL2 FROM TABLE WHERE COL2 IN (SELECT MAX(COL2) FROM TABLE)
Edit: There is only 1 table with COL1 and COL2 where the row with maximum value of
COL2 is the expected output
SELECT COL1,COL2
FROM TABLE
ORDER BY COL2 DESC
FETCH FIRST 1 ROW WITH TIES
This one should also work:
SELECT MAX(COL1) KEEP (DENSE_RANK LAST ORDER BY COL2) as COL1,
MAX(COL2) as COL2
FROM TABLE;
Use PARTITION key find out maximum col2 with col1 as per below:
select COL1, COL2 from (
select COL1, COL2, ROW_NUMBER() over(PARTITION BY COL1 ORDER BY COL2 desc) row_num from TABLE
) where row_num=1;
Assuming COL1 can be used as candidate key -
SELECT T1.COL1,
T1.COL2
FROM TABLE1 T1
INNER JOIN TABLE1 T2
ON (T1.COL1 = T2.COL1
AND T1.COL2 >= T2.COL2)
Related
Col1
Col2
Col3
A
B
1
A
B
1
A
B
2
A
B
2
A
c
1
When col1 and Col2 values are same and Col3 values are different I dont want that values in result set.
I want result as below. I tried with row_number, group by , so manythings but did not worked. Please help me here
Col1
Col2
Col3
A
c
1
You can use exists:
delete from t
where exists (select 1
from t t2
where t2.col1 = t.col1 and t2.col2 = t.col1 and
t2.col3 <> t.col3
);
You can also use window functions:
with todelete as (
select t.*,
min(col3) over (partition by col1, col2) as min_col3,
max(col3) over (partition by col1, col2) as min_col4
from t
)
delete from todelete
where min_col3 <> max_col3;
Best way is to make these column a unique composite key. But here is a query to delete all records other than your desired result.
delete from Table_1
where
Col1=(SELECT Col1
FROM table_1
GROUP BY Col1, Col2
HAVING Count(*) > 1)
And
Col2 =(SELECT Col2
FROM table_1
GROUP BY Col1, Col2
HAVING Count(*) > 1)
this might not be the most optimized and efficient query but it works. if you don't want to delete duplicated records and just retrieve unique ones:
SELECT Col1,Col2
FROM table_1
GROUP BY Col1, Col2
HAVING Count(*) = 1
To get duplicating records:
SELECT Col2,Col1
FROM table_1
GROUP BY Col1, Col2
HAVING Count(*) > 1
I need to find all the rows where col2 has same value but col3 has a different value .From the table above , It should return Pk1,Pk3 and Pk4. I tried the following a self join but i see duplicate records .
SELECT T1.COL1,T1.COL2,T1.COl3
FROM Tab T1, Tab T2
WHERE T1.Col2=T2.Col1
AND T1.Col3 <> T2.Col3
;
I would use exists:
select t.*
from t
where exists (select 1 from t t2 where t2.col2 = t.col2 and t2.col3 <> t.col3);
Analytic functions are better for this kind of job - they avoid all joins. For example:
select col1, col2, col3
from (
select t.*,
case when min(col3) over (partition by col2) !=
max(col3) over (partition by col2) then 0 end as flag
from tab t
)
where flag = 0;
It is not entirely clear how you want to handle null in col3 - does that count as a "different" value? What if you have null more than once (for the same value in col2)? Also - what if col2 can be null?
Try this:
SELECT COL1,COL2,COL3 FROM
(SELECT COL1,COL2,COL3, COUNT(DISTINCT COL3) OVER (PARTITION BY COL2) CNT
FROM TEST)
WHERE CNT > 1
db<>fiddle demo
Cheers!!
I need to delete the repeated row-
I have this table-
source
The result that I need-
result
*keep only one combination of 2 column (the order is not important)
Thanks! (:
Here is one method that should be efficient:
select col1, col2
from t
where col1 <= col2
union all
select col1, col2
from t
where col1 > col2 and
not exists (select 1 from t t2 where t2.col1 = t.col2 and t2.col2 = t.col1);
Note: This is a SQL select statement, so it does not delete rows in the table. You seem to want the results from a query, not to modify the underlying table.
My interpretation of the spec "keep only one combination of 2 column, [column] order not important":
SELECT col1, col2
FROM t
WHERE col1 <= col2
UNION
SELECT col2, col1
FROM t
WHERE col1 > col2;
SELECT DISTINCT col1, col2 FROM table t ORDER BY col1;
This gives me distinct combination of col1 & col2. Is there an alternative way of writing the Oracle SQL query to get the unique combination of col1 & col2 records with out using the keyword distinct?
Use the UNIQUE keyword which is a synonym for DISTINCT:
SELECT UNIQUE col1, col2 FROM table t ORDER BY col1;
I don't see why you would want to but you could do
SELECT col1, col2 FROM table_t GROUP BY col1, col2 ORDER BY col1
Another - yet overly complex and somewhat useless - solution:
select *
from (
select col1,
col2,
row_number() over (partition by col1, col2 order by col1, col2) as rn
from the_table
)
where rn = 1
order by col1
select col1, col2
from table
group by col1, col2
order by col1
or a less elegant way:
select col1,col2 from table
UNION
select col1,col2 from table
order by col1;
or a even less elegant way:
select a.col1, a.col2
from (select col1, col2 from table
UNION
select NULL, NULL) a
where a.col1 is not null
order by a.col1
Yet another ...
select
col1,
col2
from
table t1
where
not exists (select *
from table t2
where t2.col1 = t1.col1 and
t2.col2 = t1.col2 and
t2.rowid > t1.rowid)
order by
col1;
Variations on the UNION solution by #aF. :
INTERSECT
SELECT col1, col2 FROM tableX
INTERSECT
SELECT col1, col2 FROM tableX
ORDER BY col1;
MINUS
SELECT col1, col2 FROM tableX
MINUS
SELECT col1, col2 FROM tableX WHERE 0 = 1
ORDER BY col1;
MINUS (2nd version, it will return one row less than the other versions, if there is (NULL, NULL) group)
SELECT col1, col2 FROM tableX
MINUS
SELECT NULL, NULL FROM dual
ORDER BY col1;
Another ...
select col1,
col2
from (
select col1,
col2,
rowid,
min(rowid) over (partition by col1, col2) min_rowid
from table)
where rowid = min_rowid
order by col1;
So I have a table with three columns - col1, col2 and col3. I need to select those values of col1 that share rows with only one combinarion of col2 and col3. In ideal world I would write this:
SELECT col1 FROM table
GROUP BY col1
HAVING COUNT(DISTINCT(col2, col3)) = 1
How to do that in the real world?
So far I have two solutions - group by col1 and col2 and by col1 and col3 them join results; or group by all three then group that by col1. Unfortunately I get (very) different wor counts.
The database is on SQL Server 2005.
SELECT col1
FROM table
GROUP BY col1
HAVING MAX(col2) = MIN(col2) AND MAX(col3) = MIN(col3)
More complex:
SELECT col1
FROM
(
SELECT
col1,
ROW_NUMBER() OVER (PARTITION BY col1 ORDER BY col2, col3) as rn
FROM table
) T
GROUP BY col1
HAVING MAX(rn) = 1
select *
from mycols
where col1 in (
select max(col1)
from mycols
group by col2, col3
having count(col1)=1
)