Here is my table data...lets call this table TABLEX
ID COL1 COL2
------------------------------
100 a b
101 x y
102 a b
103 c d
104 e f
105 a b
106 c d
107 x y
I want following records to be retrieved from this table
ID COL1 COL2
------------------------------
100 a b
101 x y
103 c d
104 e f
In other words I want to retrieve distinct values from COL1 + COL2 but also show along with records' ID.
select min(id) as id, col1, col2
from Tablex
group by col1, col2
I have observed the you return the lowest ID for every the same col and col2.
SELECT MIN(ID) `ID`, col1, col2
FROM tableName
GROUP BY col1, col2
You haven't said how you want to select which record ID to display for a given set of values. Your sample implies you want the lowest one.
SELECT MIN(id) as id, col1, col2
FROM your_table
GROUP BY col1,cold2
ORDER BY MIN(id)
Related
I have the following table with Postgres:
Id Col1 Col2 Col3
1 A 1 x
2 A 0 y
3 A 0 z
4 B 0 x
5 B 1 y
6 C 0 z
As part of a select query, I want to be able to drop duplicates in Col1, based on the highest Col2 values (where will never be multiple highest values per Col1 value), and keep the corresponding Col2, Col3 values.
Desired output:
Id Col1 Col2 Col3
1 A 1 x
5 B 1 y
6 C 0 z
In Postgres, you can use distinct on:
select distinct on (col1) t.*
from t
order by col1, col2 desc;
I have a dataset like
col1 col2 col3
A x 1
A x 2
A x 3
B y 4
B -y 5
B y 6
C -z 7
C z 8
C -z 9
D t 10
D t 11
D t 12
how can i pick out just the groups from col1 that have distinct values in col2? So A,D in this case.
something like
select * from table t1
where (select count(distinct col2)
from table t2
where t1.col1 = t2.col1) > 1
but more optimized?
If all you need is the column col1 you can group by col1 and set the condition in the HAVING clause:
SELECT col1
FROM tablename
GROUP BY col1
HAVING COUNT(DISTINCT col2) = 1;
If you want all the rows from the table use the above query with the operator IN:
SELECT *
FROM tablename
WHERE col1 IN (
SELECT col1
FROM tablename
GROUP BY col1
HAVING COUNT(DISTINCT col2) = 1
)
You can use group by and having:
select col1
from t
group by col1
having min(col2) <> max(col2);
Let's say I have a table with col1 and col2
I group by col1 and order by col1
From the first group, I want to have all values of col2 but from the second group, I want to have only those values which were present in the first group and so on with the consecutive groups.
sample table
col1 col2
1 A
1 B
1 C
1 D
2 E
2 A
2 B
2 G
3 B
3 D
And the output should be
col1 col2
1 A
1 B
1 C
1 D
2 A
2 B
3 B
You can use window functions in order to avoid to read the same table twice:
Number the groups to make sure to have 1, 2, 3, ... without gaps.
Get a rolling count of col2, or in other words the cumulated numbers of their appearances.
Only show rows where the group number equals the count.
The query:
select col1, col2
from
(
select
col1, col2,
dense_rank() over (order by col1) as rn,
count(*) over (partition by col2 order by col1) as cnt
from mytable
) numbered_and_counted
where rn = cnt
order by col1, col2;
Demo: https://dbfiddle.uk/?rdbms=oracle_18&fiddle=f0cc6a211a1a4c767c9e3ce9deb8c28f
My table:
Col1 Col2
1 xyz
1 abc
2 abc
3 yyy
4 zzz
4 zzz
I have a table with two columns. I want to query for records where col1 has more than one DISTINCT col2 values. In the example table given above, the query should return records for col1 with value "1".
Expected query result:
Col1 Col2
1 xyz
1 abc
SELECT *
FROM tableName
WHERE Col1 IN
(
SELECT Col1
FROM tableName
GROUP BY Col1
HAVING COUNT(DISTINCT col2) > 1
)
SQLFiddle Demo
select t.col1, t.col2
from (
select col1
from tbl
group by col1
having MIN(col2) <> MAX(col2)
) x
join tbl t on t.col1 = c.col1
See the below table:
col1 col2
---- ----
1 | a
2 | b
3 | c
4 | a
5 | d
6 | b
7 | e
Now I want to show only the non-duplicate records. which means 3,5,7.
How to write a query to get the result?
SELECT col1, col2
FROM table
GROUP BY col2
HAVING COUNT(*) = 1;
SELECT B.*
FROM
(
SELECT col2
FROM YOURTABLE
GROUP BY col2
HAVING COUNT(*)=1
) A,
YOURTABLE B
WHERE A.col2 = B.col2
SELECT count(*) as cnt,col1, col2
FROM table
GROUP BY col2
HAVING cnt = 1;
Believe this is clear and correct enough:
SELECT *
FROM table
WHERE
col2 IN (SELECT col2 FROM table GROUP BY col2 HAVING COUNT(*) = 1)