For example, I have a table below
+-----------+-------+------------+
| Id | a| b|
+-----------+-------+------------+
| 1 | 6 | 20 |
| 1 | 4 | 55 |
| 1 | 9 | 56 |
| 1 | 2 | 67 |
| 1 | 7 | 80 |
| 1 | 5 | 66 |
| 1 | 3 | 33 |
| 1 | 8 | 34 |
| 1 | 1 | 52 |
I want the output would be like below by using Impala
+-----------+-------------------+-----------------------------+
| Id | a | b |
+-----------+-------------------+-----------------------------+
| 1 | 6,4,9,2,7,5,3,8,1 | 20,55,56,67,80,66,33,34,52 |
+-----------+-------------------+-----------------------------+
In Impala, I have used
SELECT Id,
group_concat(DISTINCT a) AS a,
group_concat(DISTINCT b) AS b
FROM table GROUP BY Id
It will always get Syntax error. Just wondering is that we are not allowed to use multi group_concat for one query in Impala? or not allow to use multi Distinct for one query?
From the documentation for GROUP_CONCAT:
You cannot apply the DISTINCT operator to the argument of this function.
But, as workaround, we can use two separate subqueries to find the distinct values:
WITH cte1 AS (
SELECT Id, GROUP_CONCAT(a) AS a
FROM (SELECT DISTINCT Id, a FROM yourTable) t
GROUP BY Id
),
cte2 AS (
SELECT Id, GROUP_CONCAT(b) AS b
FROM (SELECT DISTINCT Id, b FROM yourTable) t
GROUP BY Id
)
SELECT
t1.Id,
t1.a,
t2.b
FROM cte1 t1
INNER JOIN cte2 t2
ON t1.Id = t2.Id;
Related
I have a problem with grouping data in postgresql. let say that I have table called my_table
some_id | description | other_id
---------|-----------------|-----------
1 | description-1 | a
1 | description-2 | b
2 | description-3 | a
2 | description-4 | a
3 | description-5 | a
3 | description-6 | b
3 | description-7 | b
4 | description-8 | a
4 | description-9 | a
4 | description-10 | a
...
I would like to group my database based on some_id then differentiate which one has same and different other_id
I would expecting 2 type of queries: 1 that has same other_id and 1 that has different other_id
Expected result
some_id | description | other_id
---------|-----------------|-----------
2 | description-3 | a
2 | description-4 | a
4 | description-8 | a
4 | description-9 | a
4 | description-10 | a
AND
some_id | description | other_id
---------|-----------------|-----------
1 | description-1 | a
1 | description-2 | b
3 | description-5 | a
3 | description-6 | b
3 | description-7 | b
I am open for suggestion both using sequelize or raw query
thank you
One approach, using MIN and MAX as analytic functions:
WITH cte AS (
SELECT *, MIN(other_id) OVER (PARTITION BY some_id) min_other_id,
MAX(other_id) OVER (PARTITION BY some_id) max_other_id
FROM yourTable
)
-- all some_id the same
SELECT some_id, description, other_id
FROM cte
WHERE min_other_id = max_other_id;
-- not all some_id the same
SELECT some_id, description, other_id
FROM cte
WHERE min_other_id <> max_other_id;
Demo
You can also do this using exists and not exists:
-- all same
select t.*
from my_table t
where not exists (select 1
from my_table t2
where t2.some_id = t.some_id and t2.other_id <> t.other_id
);
-- any different
select t.*
from my_table t
where exists (select 1
from my_table t2
where t2.some_id = t.some_id and t2.other_id <> t.other_id
);
Note that this ignores NULL values. If you want them treated as a "different" value then use is distinct from rather than <>.
Given this table I want to retrieve for each different url the row with the maximum count. For this table the output should be: 'dell.html' 3, 'lenovo.html' 4, 'toshiba.html' 5
+----------------+-------+
| url | count |
+----------------+-------+
| 'dell.html' | 1 |
| 'dell.html' | 2 |
| 'dell.html' | 3 |
| 'lenovo.html' | 1 |
| 'lenovo.html' | 2 |
| 'lenovo.html' | 3 |
| 'lenovo.html' | 4 |
| 'toshiba.html' | 1 |
| 'toshiba.html' | 2 |
| 'toshiba.html' | 3 |
| 'toshiba.html' | 4 |
| 'toshiba.html' | 5 |
+----------------+-------+
What SQL query do I need to write to do this?
Try to use this query:
select url, max(count) as count
from table_name
group by url;
use aggregate function
select max(count) ,url from table_name group by url
From your comments it seems you need corelated subquery
select t1.* from table_name t1
where t1.count = (select max(count) from table_name t2 where t2.url=t1.url
)
If row_number support on yours sqllite version
then you can write query like below
select * from
(
select *,row_number() over(partition by url order by count desc) rn
from table_name
) a where a.rn=1
I am having a table having records like this:
+------+------+
| ID | name |
+------+------+
| 1 | A |
| 2 | B |
| 3 | C |
| 4 | A |
| 5 | B |
| 6 | A |
| 7 | A |
| 8 | A |
+------+------+
I need to get value of A after it was last updated from a different value, for example here it would be the row at ID 6.
Try this query (MySQL syntax):
select min(ID)
from records
where name = 'A'
and ID >=
(
select max(ID)
from records
where name <> 'A'
);
Illustration:
select * from records;
+------+------+
| ID | name |
+------+------+
| 1 | A |
| 2 | B |
| 3 | C |
| 4 | A |
| 5 | B |
| 6 | A |
| 7 | A |
| 8 | A |
+------+------+
-- run query:
+---------+
| min(ID) |
+---------+
| 6 |
+---------+
Using the Lag function...
SELECT Max([ID])
FROM (SELECT [name], [ID],
Lag([name]) OVER (ORDER BY [ID]) AS PrvVal
FROM tablename) tbl
WHERE [name] = 'A'
AND prvval <> 'A'
Online Demo: http://www.sqlfiddle.com/#!18/a55eb/2/0
If you want to get the whole row, you can do this...
SELECT Top 1 *
FROM (SELECT [name], [ID],
Lag([name]) OVER (ORDER BY [ID]) AS PrvVal
FROM tablename) tbl
WHERE [name] = 'A' AND prvval <> 'A'
ORDER BY [ID] DESC
Online Demo: http://www.sqlfiddle.com/#!18/a55eb/22/0
The ANSI SQL below uses a self-join on the previous id.
And the where-clause gets those with a name that's different from the previous.
select max(t1.ID) as ID
from YourTable as t1
left join YourTable as t2 on t1.ID = t2.ID+1
where (t1.name <> t2.name or t2.name is null)
and t1.name = 'A';
It should work on most RDBMS, including MS Sql Server.
Note that with the ID+1 that there's an assumption that are no gaps between the ID's.
I have two tables:
Table #1 - Student:
+------+-------+
|Roll | Name |
+------+-------+
| 1 | A |
| 2 | B |
| 3 | C |
+------+-------+
Table #2 - Mark:
+------+------+
| Roll | Mark |
+------+------+
| 1 | 85 |
| 3 | 95 |
+------+------+
Output needs to be:
+-------+------+-------+---------+
| Roll | Name | Mark |Position |
+-------+------+-------+---------+
| 1 | A | 85 | 2 |
| 2 | B | 0 | 3 |
| 3 | C | 95 | 1 |
+-------+------+-------+---------+
What should be the query to get the output? I think the rank function is to be used, but don't know to use it...
Use LEFT JOIN to join two tables and then use RANK().
Query
select *, Position = rank() over(
order by t.Mark desc
)
from(
select t1.Roll, t1.Name, coalesce(t2.Mark, 0) as Mark
from student t1
left join Mark t2
on t1.Roll = t2.Roll
)t
order by t.Name;
Use Left Join and Rank() function.
Query
select T1.Roll, T1.Name, isnull(T2.Mark,0) Mark, rank() over(order by mark desc) Position
from STUDENT T1 left join MARK T2
on T1.Roll = T2.Roll order by T1.Roll
I have to get a specific output format from my tables.
Let's say I have a simple table with 2 columns name and value.
table T1
+---------------+------------------+
| Name | Value |
+---------------+------------------+
| stuff1 | 1 |
| stuff1 | 1 |
| stuff2 | 2 |
| stuff3 | 1 |
| stuff2 | 4 |
| stuff2 | 2 |
| stuff3 | 4 |
+---------------+------------------+
I know the values are in the interval 1-4. I group it by name and value and count number of the same rows as Number and get the following table:
table T2
+---------------+------------------+--------+
| Name | Value | Number |
+---------------+------------------+--------+
| stuff1 | 1 | 2 |
| stuff2 | 2 | 2 |
| stuff3 | 1 | 1 |
| stuff3 | 4 | 1 |
+---------------+------------------+--------+
Here is the part when I need your help! What should I do if I want to get these format?
table T3
+---------------+------------------+--------+
| Name | Value | Number |
+---------------+------------------+--------+
| stuff1 | 1 | 2 |
| stuff1 | 2 | 0 |
| stuff1 | 3 | 0 |
| stuff1 | 4 | 0 |
| stuff2 | 1 | 0 |
| stuff2 | 2 | 2 |
| stuff2 | 3 | 0 |
| stuff2 | 4 | 0 |
| stuff3 | 1 | 1 |
| stuff3 | 2 | 0 |
| stuff3 | 3 | 0 |
| stuff3 | 4 | 1 |
+---------------+------------------+--------+
Thanks for any suggestions!
You start with a cross join to generate all possible combinations and then left-join in the results from your existing query:
select n.name, v.value, coalesce(nv.cnt, 0) as "Number"
from (select distinct name from table t) n cross join
(select distinct value from table t) v left outer join
(select name, value, count(*) as cnt
from table t
group by name, value
) nv
on nv.name = n.name and nv.value = v.value;
Variation on the theme.
Differences between Gordon Linoff and Owen existing answers.
I prefer GROUP BY to get the Names rather than a DISTINCT. This may have better performance in a case like this. (See Rob Farley's still relevant article.)
I explode the subqueries into a series of CTEs for clarity.
I use table T2 as the question now labels the group results set instead of showing that as as subquery.
WITH PossibleValue AS (
SELECT 1 Value
UNION ALL
SELECT Value + 1
FROM PossibleValue
WHERE Value < 4
),
Name AS (
SELECT Name
FROM T1
GROUP BY Name
),
NameValue AS (
SELECT Name
,Value
FROM Name
CROSS JOIN
PossibleValue
)
SELECT nv.Name
,nv.Value
,ISNULL(T2.Number,0) Number
FROM NameValue nv
LEFT JOIN
T2 ON nv.Name = T2.Name
AND nv.Value = T2.Value
Yet another solution, this time using a Table Value Constructor in a CTE to build a table of name value combinations.
WITH value AS
( SELECT DISTINCT t.name, v.value
FROM T1 AS t
CROSS JOIN (VALUES (1),(2),(3),(4)) AS v (value)
)
SELECT v.name AS 'Name', v.value AS 'Value', COUNT(t.name) AS 'Number'
FROM value AS v
LEFT JOIN T1 AS t ON t.value = v.value AND t.name = v.name
GROUP BY v.name, v.value, t.name;