Given the following table:
id | group_s | name
_____________________
1 | 1 | pollo
2 | 1 | cordero
3 | 1 | cerdo
4 | 2 | tomates
5 | 2 | naranjas
6 | 2 | manzanas
I would like to randomly select one line from every group.
Example of possible outputs (since it is random):
id | group_s | name
_____________________
3 | 1 | cerdo
5 | 2 | naranjas
or
id | group_s | name
_____________________
1 | 1 | pollo
6 | 2 | manzanas
and so on..
I don't have a clue how to do it. I suppose I should multiselect the table.
I did try the following without success:
SELECT T2.* FROM (
SELECT group_s
FROM mytable
GROUP BY group_s ORDER BY RAND() LIMIT 1) AS T1
JOIN mytable AS T2
ON T1.group_s = T2.group_s;
Use the window function ROW_NUMBER() OVER(PARTITION BY group_s) with ORDER BY NEWID() to randomly get the ordering, something like this:
WITH CTE
AS
(
SELECT *,
ROW_NUMBER() OVER(PARTITION BY group_s
ORDER BY newid()) AS RN
FROM yourTable
)
SELECT id , group_s , name
FROM CTE
WHERE RN = 1;
See it in action here:
SQL Fiddle Demo
Related
table 1 t1
+----+----------+
| id | name |
+----+----------+
| 1 | free |
| 2 | basic |
| 3 | advanced |
+----+----------+
table 2 t2
+----+-------+------+
| id | t1_fk | cost |
+----+-------+------+
| 1 | 2 | 1650 |
| 3 | 3 | 2000 |
| 4 | 2 | 550 |
+----+-------+------+
I want to get the output of t2 table but without duplicates. I was able to get this using GROUP BY function. Also i need the last item on the duplicate (i got stuck here).
Here's what i tried and it didn't work.
SELECT id cost FROM t2 GROUP BY t1_fk ORDER BY MAX(id) DESC
any help
On MySQL 8+, we can use ROW_NUMBER here:
WITH cte AS (
SELECT *, ROW_NUMBER() OVER (PARTITION BY t1_fk ORDER BY id DESC) rn
FROM t2
)
SELECT id, t1_fk, cost
FROM cte
WHERE rn = 1;
On earlier versions of MySQL, one canonical way to handle this would be to use a join to a subquery which finds the max id value for each t1_fk:
SELECT a.id, a.t1_fk, a.cost
FROM t2 a
INNER JOIN
(
SELECT t1_fk, MAX(id) AS max_id
FROM t2
GROUP BY t1_fk
) b
ON a.t1_fk = b.t1_fk AND a.id = b.max_id;
I have a table like so (I'm not sure how to format tables)
Category / Products / Purchases
1 | A | 12
1 | B | 13
1 | C | 11
2 | A | 1
2 | B | 2
2 | C | 3
Expected output:
1 | B | 13
2 | C | 3
However I keep on getting
1 | A | 13
2 | A | 3
ie. It just selects the first occurrence of the second column.
Here is my code:
SELECT Category, Products, MAX(Purchases) FROM myTable GROUP BY Category;
Use filtering in the where clause:
select t.*
from t
where t.purchases = (select max(t2.purchases) from t t2 where t2.category = t.category);
With NOT EXISTS:
select m.* from myTable m
where not exists (
select 1 from myTable
where category = m.category and purchases > m.purchases
)
See the demo.
Results:
| Category | Products | Purchases |
| -------- | -------- | --------- |
| 1 | B | 13 |
| 2 | C | 3 |
You can use row_number() to identify max purchase for each group or replace rownumber() to rank() if there are ties of max purchases for each group
Select Category, Products,
Purchases from (Select Category,
Products,
Purchases,
row_number() over (partition by
category, products order by
purchases desc) rn from table) t
where t.rn=1
)
resulttable:
+-------------+-----------+
| resultSetID | projectID |
+-------------+-----------+
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 2 | 1 |
| 2 | 2 |
| 3 | 1 |
| 3 | 2 |
| 3 | 3 |
+-------------+-----------+
Query:
SELECT
COUNT( projectID )
FROM
resulttable
WHERE
projectID = 3
... correctly returns 2. However, I want the counts of each ID without using the WHERE condition, how do I do that?
Do you just want group by?
SELECT projectId, COUNT( * )
FROM resulttable
GROUP BY projectID;
The following query is used to get all the data for the projectId but if you want to get a specific query data without where you can use having instead
SELECT projectId, COUNT( * )
FROM resulttable
GROUP BY projectId having projectId = 3;
The following query should work for you:
SELECT projectID, SUM(resultSetID)
FROM resulttable
GROUP BY projectID;
I am trying to create a query that allows me to select the data like shown below
id Counter_Type Champion_Name Counter_Lane
---|------------|------------|--------------
1 | 1 | Ahri | 1
2 | 1 | Ahri | 2
5 | 1 | Ahri | 2
3 | 1 | Ahri | 3
4 | 1 | Ahri | 2
6 | 1 | Teemo | 1
7 | 1 | Warwick | 4
8 | 1 | Warwick | 4
It should count the Counter_Lane and then the Counter_Type with the most should be shown for that name as shown below how it should show the data:
id Counter_Type Champion_Name Counter_Lane
---|------------|------------|--------------
1 | 1 | Ahri | 2
2 | 1 | Teemo | 1
3 | 1 | Warwick | 4
I have tried the following code and its the closest I have came for over 3 hours now, so could someone help please.
SELECT
a.Counter_Type, Champion_For, a.Counter_Lane, a.Champion_Name, COUNT(*) as Amount, sum(vote_type = 'up') as Upvotes, sum(vote_type = 'down') as Downvotes, sum(vote_type = 'up')-sum(vote_type = 'down') as Totalvotes
FROM Champion_Counters_Data a
JOIN ( SELECT c.Counter_Lane, c.Champion_Name, COUNT(*) magnitude
FROM Champion_Counters_Data c
WHERE
Champion_For = "Aatrox" AND Counter_Type = 1 GROUP BY Champion_Name, Counter_Lane ORDER BY magnitude) b ON a.Champion_Name = b.Champion_Name AND b.Counter_Lane = a.Counter_Lane
GROUP BY Champion_Name
SELECT * FROM your_table GROUP BY MAX(Counter_Lane)
This query is based on the output you want from the table you have given.
You will need many subqueries as MySQL doesn't allow windows function or CTE.
Rextester Demo
SELECT #rn := #rn + 1 as id,
t3.*
from
(select t1.*
FROM
(SELECT counter_type,
champion_name,
counter_lane,
count(*) AS cnt
FROM table53
GROUP BY champion_name,
counter_lane
) t1
INNER JOIN
(SELECT counter_type,
champion_name,
max(cnt) AS mcnt
FROM
(SELECT counter_type,
champion_name,
counter_lane,
count(*) AS cnt
FROM table53
GROUP BY champion_name,
counter_lane
) t
GROUP BY counter_type,
champion_name
) t2
ON t1.counter_type=t2.counter_type
AND t1.champion_name=t2.champion_name
AND t1.cnt=t2.mcnt
) t3
,(SELECT #rn := 0) t
;
Output
+-----+--------------+---------------+--------------+-----+
| id | counter_type | champion_name | counter_lane | cnt |
+-----+--------------+---------------+--------------+-----+
| 1 | 1 | Ahri | 2 | 3 |
| 2 | 1 | Teemo | 1 | 1 |
| 3 | 1 | Warwick | 4 | 2 |
+-----+--------------+---------------+--------------+-----+
Idea is to first group by champion_name and counter_lane and get the count . So for Ahri you will get cnt as 3. Now use another subquery to get corresponding counter_lane, which will be 2 for Ahri. At last, use a sequence number to generate id as 1,2,3 etc.
Try following SQL statement:
SELECT Counter_Type , Champion_Name, MAX(Counter_Lane) 'Counter_Lane'
FROM(
SELECT Counter_Type , Champion_Name , Counter_Lane
FROM Champion_Counters_Data
GROUP BY Counter_Type , Champion_Name
HAVING COUNT(Counter_Lane) >= 2
) tb
GROUP BY Counter_Type , Champion_Name
Table Mytable1
Id | Actual
1 ! 10020
2 | 12203
3 | 12312
4 | 12453
5 | 13211
6 | 12838
7 | 10l29
Using the following syntax:
SELECT AVG(Actual), CEIL((#rank:=#rank+1)/3) AS rank FROM mytable1 Group BY rank;
Produces the following type of result:
| AVG(Actual) | rank |
+-------------+------+
| 12835.5455 | 1 |
| 12523.1818 | 2 |
| 12343.3636 | 3 |
I would like to take AVG(Actual) column and UPDATE a second existing table Mytable2
Id | Predict |
1 | 11133
2 | 12312
3 | 13221
I would like to get the following where the Actual value matches the ID as RANK
Id | Predict | Actual
1 | 11133 | 12835.5455
2 | 12312 | 12523.1818
3 | 13221 | 12343.3636
IMPORTANT REQUIREMENT
I need to set an offset much like the following syntax:
SELECT #rank := #rank + 1 AS Id , Mytable2.Actual FROM Mytable LIMIT 3 OFFSET 4);
PLEASE NOTE THE AVERAGE NUMBER ARE MADE UP IN EXAMPLES
you can join your existing query in the UPDATE statement
UPDATE Table2 T2
JOIN (
SELECT AVG(Actual) as AverageValue,
CEIL((#rank:=#rank+1)/3) AS rank
FROM Table1, (select #rank:=0) t
Group BY rank )T1
on T2.id = T1.rank
SET Actual = T1.AverageValue