I know the basics in SQL programming and I know how to apply some tricks in SQL Server in order to get the result set, but I don't know all tricks in Oracle.
I have these columns:
col1 col2 col3
And I wrote this query
SELECT
col1, MAX(col3) AS mx3
FROM
myTable
GROUP BY
col1
And I need to get the value of col2 in the same row where I found the max value of col3, do you know some trick to solve this problem?
The easiest way to do this, IMHO, is not to use max, but the window function rank:
SELECT col1 , col2, col3
FROM (SELECT col1, col2, col3,
RANK() OVER (PARTITION BY col1 ORDER BY col3 DESC) rk
FROM myTable) t
WHERE rk = 1
BTW, the same syntax should also work for MS SQL-Server and most other modern databases, with MySQL being the notable exception.
A couple of different ways to do this:
In both cases I'm treating your initial query as either a common table expression or as an inline view and joining it back to the base table to get your added column. The trick here is that the INNER JOIN eliminates all the records not in your max query.
SELECT A.*,
FROM myTable A
INNER JOIN (SELECT col1 , MAX( col3 ) AS mx3 FROM myTable GROUP BY col1) B
on A.Col1=B.Col1
and B.mx3 = A.Col3
or
with CTE AS (SELECT col1 , MAX( col3 ) AS mx3 FROM myTable GROUP BY col1)
SELECT A.*
FROM MyTable A
INNER JOIN CTE
on A.col1 = B.Col1
and A.col3= cte.mx3
Here's an alternative that's just a slight extension of your existing group by query (ie. doesn't require querying the same table more than once):
with mytable as (select 1 col1, 1 col2, 1 col3 from dual union all
select 1 col1, 2 col2, 2 col3 from dual union all
select 1 col1, 1 col2, 3 col3 from dual union all
select 1 col1, 3 col2, 3 col3 from dual union all
select 2 col1, 10 col2, 1 col3 from dual union all
select 2 col1, 23 col2, 2 col3 from dual union all
select 2 col1, 12 col2, 2 col3 from dual)
SELECT
col1,
MAX(col2) keep (dense_rank first order by col3 desc) mx2,
MAX(col3) AS mx3
FROM
myTable
GROUP BY
col1;
COL1 MX2 MX3
---------- ---------- ----------
1 3 3
2 23 2
Related
I have a table with three columns (id, col2, col3, col4) where col2 is A or B and col3 and col4 are integers. My problem is, there are many columns that have the same id and a different col2 value, and I want to select ONLY the rows that have a maximum value in col3.
For instance, if we have:
id | col2 | col3 | col4
1 | A | 3 | 2
1 | B | 5 | 3
2 | A | 6 | 2
...
I want to keep only the tuple (1, B, 5, 3). How can I achieve this?
I've tried this:
SELECT id, col2, MAX(col3), col4 FROM t GROUP BY id;
but I get an error saying that this is not a valid GROUP BY statement.
You can use keep:
SELECT id,
MAX(col2) KEEP (DENSE_RANK FIRST ORDER BY col3 DESC) as col2
MAX(col3),
MAX(col4) KEEP (DENSE_RANK FIRST ORDER BY col3 DESC) as col4
FROM t
GROUP BY id;
Or:
SELECT id, col2, col3, col4
FROM (SELECT t.*,
ROW_NUMBER() OVER (PARTITION BY id ORDER BY col3 DESC) as seqnum
FROM t
) t
WHERE seqnum = 1;
This query:
select t.*
from tablename t inner join (
select id, max(col3) col3
from tablename
group by id
having count(distinct col2) > 1
) g on g.id = t.id and g.col3 = t.col3
returns for each id that has different values in col2 only 1 row: the one containing the maximum value of col3.
If you also want the other rows where each id does not have different values in col2, then use UNION ALL:
select t.*
from tablename t inner join (
select id, max(col3) col3
from tablename
group by id
having count(distinct col2) > 1
) g on g.id = t.id and g.col3 = t.col3
union all
select t.* from tablename t
where not exists (
select 1 from tablename
where id = t.id and col2 <> t.col2
)
select * from TableName where col3 = (select max(col3) from TableName)
I'm have a table with many columns in BigQuery.
I wanna list its columns in select query, but listing the all columns is hard.
I wanna do like this
SELECT
col1,
col2,
col3,
...
SOME_METHOD(col30),
...
col50
FROM
foo.bar;
Is there any ways to write such query easily?
Below is for BigQuery Standard SQL
SELECT * EXCEPT(col30), SOME_METHOD(col30)
FROM foo.bar
or
SELECT * REPLACE(SOME_METHOD(col30) as col30)
FROM foo.bar
for example
#standardSQL
WITH `project.dataset.table` AS (
SELECT 1 col1, 2 col2, 3 col3, 4 col4, 5 col5
)
SELECT * EXCEPT(col3), 2 * col3 AS col3
FROM `project.dataset.table`
with result
Row col1 col2 col4 col5 col3
1 1 2 4 5 6
or
#standardSQL
WITH `project.dataset.table` AS (
SELECT 1 col1, 2 col2, 3 col3, 4 col4, 5 col5
)
SELECT * REPLACE(2 * col3 AS col3)
FROM `project.dataset.table`
with result
Row col1 col2 col3 col4 col5
1 1 2 6 4 5
This is untested in Big Query, but one trick which is available in other databases, such as SQL Server, is to do a SELECT *, but then also list other items you want to select. So you may try one of the following:
SELECT *, SOME_METHOD(col30) AS output
FROM yourTable;
Or
SELECT SOME_METHOD(col30), * AS output
FROM yourTable;
Note that depending on what the other things are you explicitly list, you could end up with the same column (and name) appearing more than once in the result set.
WE have below data in oracle database -
col1 col2
Z1 A
Z1 B
Z2 A
Z2 C
Z3 A
Z4 D
I want count on column two in such a way that -
Ouput -
col2 count
A 3 (Z1,Z2,Z3)
B 0 (Dont count if A is already present for record)
C 0
D 1 (Z4)
Best Regards
You can use window function rank() to achieve this.
select col2, count(case when rn = 1 then 1 end) cnt from (
select t.*,
rank() over (partition by col1 order by case when col2 = 'A' then 1 else 2 end) rn
from table t
) group by col2;
The most general solution to your propositions where each key COL1 is counted only in the first occurrence of the key COL2 (in alphabetical order)
WITH tab AS
(
SELECT 'Z1' col1, 'A' col2 FROM dual UNION ALL
SELECT 'Z1' col1, 'B' col2 FROM dual UNION ALL
SELECT 'Z2' col1, 'A' col2 FROM dual UNION ALL
SELECT 'Z2' col1, 'C' col2 FROM dual UNION ALL
SELECT 'Z3' col1, 'A' col2 FROM dual UNION ALL
SELECT 'Z4' col1, 'D' col2 FROM dual
), tab2 as (
select COL1, COL2,
row_number() over (partition by COL1 order by COL2) as rn
from tab)
select COL1, COL2,
case when rn = 1 then 1 else 0 end is_valid
from tab2
order by 1,2
;
COL1 COL2 IS_VALID
---- ---- ----------
Z1 A 1
Z1 B 0
Z2 A 1
Z2 C 0
Z3 A 1
Z4 D 1
The rest is simple group by with a SUM on IS_VALID
select COL2, sum(is_valid) cnt from tab3 -- TAB3 is the above row source
group by COL2
order by 1
COL2 CNT
---- ----------
A 3
B 0
C 0
D 1
Thanks Guys. But I could do this way -
select count(case
when (LISTAGG(col2,'-') WITHIN GROUP (ORDER BY col2)) like '%A%' then 1
else null
end) A,
count(case
when (LISTAGG(col2,'-') WITHIN GROUP (ORDER BY col2)) = 'B' then 1
else null
end) B,
count(case
when (LISTAGG(col2,'-') WITHIN GROUP (ORDER BY col2)) = 'C' then 1
else null
end) C,
count(case
when (LISTAGG(col2,'-') WITHIN GROUP (ORDER BY col2)) = 'D' then 1
else null
end) D
from T
GROUP BY col1
Thanks for your replies
Assume your table name is table_name, One way to do it is using this:
WITH table_a AS
(
SELECT DISTINCT col1
FROM table_name
WHERE col2 = 'A'
)
SELECT col2,
SUM(CASE WHEN col1 IN (SELECT col1 FROM table_a)
THEN DECODE(col2, 'A', 1, 0)
ELSE 1 END
) count
FROM table_name
GROUP BY col2
ORDER BY col2;
Tested ok:
WITH table_name AS
(
SELECT 'Z1' col1, 'A' col2 FROM dual UNION ALL
SELECT 'Z1' col1, 'B' col2 FROM dual UNION ALL
SELECT 'Z2' col1, 'A' col2 FROM dual UNION ALL
SELECT 'Z2' col1, 'C' col2 FROM dual UNION ALL
SELECT 'Z3' col1, 'A' col2 FROM dual UNION ALL
--SELECT 'Z4' col1, 'B' col2 FROM dual UNION ALL
SELECT 'Z4' col1, 'D' col2 FROM dual
)
, table_a AS
(
SELECT DISTINCT col1
FROM table_name
WHERE col2 = 'A'
)
SELECT col2,
SUM(CASE WHEN col1 IN (SELECT col1 FROM table_a)
THEN DECODE(col2, 'A', 1, 0)
ELSE 1 END
) count
FROM table_name
GROUP BY col2
ORDER BY col2;
You want to count each record where either col2 is 'A' or no 'A' record exists for col1.
select
col2,
count(
case
when col2 = 'A' or col1 not in (select col1 from table_name where col2 = 'A') then 1
end) as cnt
from table_name
group by col2;
select col2, count(case when col2 = col3 then 'x' end) as ct
from ( select col2, min(col2) over (partition by col1) as col3
from your_table
)
group by col2
order by col2 -- if needed
;
Explanation:
There is an inner query (a.k.a. "subquery") which returns one row for each row in the original table. It returns col2 as is, and an additional (new) column, labeled col3. col3 is calculated as the "first" or min() value of col2 (in alphabetical order) for all the rows in the original table that have the same value in col1 as the current row does. This is a typical example of an analytic function; partition by col1 is similar to group by col1 but it returns all the rows in the group (all the original rows from the original table) instead of one row per group, as would an aggregate function.
To see what the inner query does by itself, select it and run it in your favorite front-end. You may add col1 to the select in the inner query - that will make what's going on in this query even clearer. You'll get the initial table, with one more column, col3, that shows the "min" col2 for each value of col1. I didn't include col1 in the subquery because I don't need it, but add it back to see what the subquery really does.
Then in the outer query I take the results from the inner query and I group by col2. For each col2 I count just how many times it is equal to the "min" value of col2 for the corresponding col1 value. That's what the case expression does in the count() function; when col2 is not equal to col3, then case returns null (by default) so the expression - and therefore the row - is not counted.
I should add that the query written this way assumes there are no duplicate (col1, col2) rows in the original table. If there are, then the inner subquery should select from a sub-subquery; line 3 of my code should be
from (select distinct col1, col2 from your_table)
Use the below script:
SELECT A.COL2, NVL(B.CNT, 0) AS CNT
FROM (SELECT DISTINCT COL2 FROM TET) A
LEFT JOIN (SELECT COL2, COUNT(COL2) AS CNT
FROM (SELECT SUBSTR(F, 1, INSTR(F, ',') - 1) AS COL2,
ROW_NUMBER() OVER(PARTITION BY SUBSTR(F, 1, INSTR(F, ',') - 1) ORDER BY SUBSTR(F, 1, INSTR(F, ',') - 1)) AS U
FROM (SELECT COL1,
LISTAGG(COL2, ',') WITHIN GROUP(ORDER BY COL2) || ',' AS F
FROM TET
GROUP BY COL1)) A
GROUP BY COL2) B
ON A.COL2 = B.COL2
ORDER BY A.COL2;
I have a requirement where I have to show data in cumulative concatenation style, just like running total by group.
Sample data
Col1 Col2
1 a
1 b
2 c
2 d
2 e
Expected output:
Col1 Col2
1 a
1 b,a
2 c
2 d,c
2 e,d,c
The concatenation needs to be broken down by Col1. Any help regarding how to get this result by Oracle SQL will be appreciated.
Assuming something on the way you need to order, this can be a solution, based on Hierarchical Queries:
with test as
(
select 1 as col1, 'a' as col2 from dual union all
select 1 as col1, 'b' as col2 from dual union all
select 2 as col1, 'c' as col2 from dual union all
select 2 as col1, 'd' as col2 from dual union all
select 2 as col1, 'e' as col2 from dual
)
select col1, col2
from (
select col1 AS col1, sys_connect_by_path(col2, ',') AS col2, connect_by_isleaf leaf
from (
select row_number() over (order by col1 asc, col2 desc) as num, col1, col2
from test
)
connect by nocycle prior col1 = col1 and prior num = num -1
)
where leaf = 1
order by col1, col2
Try:
WITH d AS (
select col1, col2,
row_number() over (partition by col1 order by col2) as x
from tab_le
),
d1( col1, col2, x, col22) as (
SELECT col1, col2, x, col2 col22 FROM d WHERE x = 1
UNION ALL
SELECT d.col1, d.col2, d.x, d.col2 || ',' || d1.col22
FROM d
JOIN d1 ON (d.col1 = d1.col1 AND d.x = d1.x + 1)
)
SELECT * FROM d1
order by 1,2;
I'm not sure you can do this with listagg as it doesn't seem to support windowing clauses. If you're on 11g or higher you can use recursive subquery factoring to achieve your result.
with your_table (col1, col2) as (
select 1, 'a' from dual
union all select 1, 'b' from dual
union all select 2, 'c' from dual
union all select 2, 'd' from dual
union all select 2, 'e' from dual
), t as (
select col1, col2, row_number() over (partition by col1 order by col2) as rn
from your_table
), r (col1, col2, rn) as (
select col1, col2, rn
from t
where rn = 1
union all
select r.col1, t.col2 ||','|| r.col2, t.rn
from r
join t on t.col1 = r.col1 and t.rn = r.rn + 1
)
select col1, col2
from r
order by col1, rn;
COL1 COL2
---------- --------------------
1 a
1 b,a
2 c
2 d,c
2 e,d,c
The your_table CTE is just to mimic your base data. The t CTE adds a row_number() analytic column to provide a sequence for the next part. The interesting part is the r recursive CTE. The anchor member starts with the first row (according to rn from the previous CTE). The recursive member then finds the next row (against according to rn) for that col1, and for that it concatenates the current col2 with the previous one, which may itself already be a concatenation.
I have the following table;
column 1 column 2 column 3
1 2 X
1 2 X
1 2 Y
1 3 Z
1 3 X
I need to write an SQL query to get the output as;
1 2 X (because X is the maximum occurrence)
1 3 Z or X(because number of occurrence of Z or X is same)
How do i do this ?
I think i have a solution for you, try this script using the functions RANK(), ROW_NUMBER() & DENSE_RANK(), you choose the function that fits with your needs :
with temp as (
select 1 as col1, 2 AS col2, 'X' as col3 union all
select 1 as col1, 2 AS col2, 'Y' as col3 union all
select 1 as col1, 2 AS col2, 'X' as col3 union all
select 1 as col1, 3 AS col2, 'Z' as col3 union all
select 1 as col1, 3 AS col2, 'T' as col3 union all
select 1 as col1, 3 AS col2, 'Y' as col3 union all
select 1 as col1, 3 AS col2, 'Y' as col3 union all
select 1 as col1, 4 AS col2, 'Y' as col3 union all
select 1 as col1, 4 AS col2, 'W' as col3)
,temp2 AS (
select
col1
,col2
,col3
,COUNT(1) nb_occurence
,RANK() OVER(PARTITION BY col1,col2 ORDER BY COUNT(1) DESC) Ordre_RANK
,ROW_NUMBER() OVER(PARTITION BY col1,col2 ORDER BY COUNT(1) DESC) Ordre_ROW_NUMBER
,DENSE_RANK() OVER(PARTITION BY col1,col2 ORDER BY COUNT(1) DESC) Ordre_DENSE_RANK
from temp
GROUP BY
col1
,col2
,col3 )
SELECT *
FROM temp2
--WHERE Ordre_RANK = 1
--WHERE Ordre_ROW_NUMBER = 1
--WHERE Ordre_DENSE_RANK = 1
I hope this will help you.