After looking at other examples I still have not been able to find a solution, that is why I am asking for some help.
My table structure:
V_id | name | group_id | other columns
----------------------
1 | | 1
2 | | 1
3 | | 2
4 | | 3
5 | | 3
I have been struggling to build a query, to select all the rows which have the maximum value from the group_id column.
therefore output should be like this:
V_id | name | group_id | other columns
----------------------
4 | | 3
5 | | 3
which I believe can be solved by selecting all records where group_id is the highest.
and also need a query to get all the other remaining rows.
which in this case, should be like this:
V_id | name | group_id | other columns
----------------------
1 | | 1
2 | | 1
3 | | 2
which I believe can be done by selecting all records where group_id < Max(group_id)
for the first part of the problem,
SELECT *
FROM tableName
WHERE group_id = (SELECT MAX(group_ID) FROM TableName)
and for the second part,
SELECT *
FROM tableName
WHERE group_id < (SELECT MAX(group_ID) FROM TableName)
You can use JOIN for that:
SELECT a.*
FROM Table1 a
JOIN (SELECT MAX(Group_ID) AS MAXID
FROM Table1) B
ON a.Group_id = B.MaxID;
Result:
| V_ID | NAME | GROUP_ID |
----------------------------
| 4 | (null) | 3 |
| 5 | (null) | 3 |
For the remaining rows use LEFT JOIN with a condition like this:
SELECT a.*
FROM Table1 a
LEFT JOIN (SELECT MAX(Group_ID) AS MAXID
FROM Table1) B
ON a.Group_id = B.MaxID
WHERE B.MaxID IS NULL;
Result:
| V_ID | NAME | GROUP_ID |
----------------------------
| 1 | (null) | 1 |
| 2 | (null) | 1 |
| 3 | (null) | 2 |
See this SQLFiddle
Related
I have two tables, namely itemOrders and itemDelivered.
itemOrders
+-------+---------+--------+
| id | orderid | itemid |
+-------+---------+--------+
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
| 4 | 2 | 2 |
| 5 | 3 | 1 |
| 6 | 3 | 2 |
+-------+---------+--------+
And
itemDelivered
+-------+-------------+--------+
| id | orderId | itemid |
+-------+-------------+--------+
| 1 | 2 | 2 |
| 2 | 3 | 2 |
| 3 | 2 | 1 |
+-------+-------------+--------+
From the above scenario I want all those distinct items whose max orderId in the table itemDelivered is less than max orderId in the table itemOrders.
In the above example I should get itemid 1 as the result, as it's max orderid is 2 in table itemDelivered, which is less than its max orderid in table itemOrders which is 3.
I wrote the following query but it gives me both the items, 1 and 2 as item No. 2 doesn't have orderId 1 in itemDelivered table.
SELECT DISTINCT( itemid )
FROM itemorders
WHERE orderid NOT IN (SELECT orderid
FROM itemdelivered)
You can LEFT JOIN between the two table using itemid, and GROUP BY on the itemid.
Eventually use HAVING clause to consider only those itemid values, where MAX(itemdelivered.orderid) < MAX(itemorders.orderid)
View on DB Fiddle
SELECT io.itemid
FROM itemorders AS io
LEFT JOIN itemdelivered AS id
ON id.itemid = io.itemid
GROUP BY io.itemid
HAVING MAX(id.orderid) < MAX(io.orderid)
OR MAX(id.orderid) IS NULL
Result
| itemid |
| ------ |
| 1 |
Ok, manage to write a query which gives the desired output.
SELECT io.itemid
FROM itemorders as io
LEFT JOIN itemdelivered AS id ON io.orderid = id.orderid AND io.itemid = id.itemid
WHERE id.itemid IS NULL
HAVING MAX(id.orderid) IS NULL
ORDER BY io.id
my table has duplicate row values in specific columns. i would like to remove those rows and keep the row with the latest id.
the columns i want to check and compare are:
sub_id, spec_id, ex_time
so, for this table
+----+--------+---------+---------+-------+
| id | sub_id | spec_id | ex_time | count |
+----+--------+---------+---------+-------+
| 1 | 100 | 444 | 09:29 | 2 |
| 2 | 101 | 555 | 10:01 | 10 |
| 3 | 100 | 444 | 09:29 | 23 |
| 4 | 200 | 321 | 05:15 | 5 |
| 5 | 100 | 444 | 09:29 | 8 |
| 6 | 101 | 555 | 10:01 | 1 |
+----+--------+---------+---------+-------+
i would like to get this result
+----+--------+---------+---------+-------+
| id | sub_id | spec_id | ex_time | count |
+----+--------+---------+---------+-------+
| 5 | 100 | 444 | 09:29 | 8 |
| 6 | 101 | 555 | 10:01 | 1 |
+----+--------+---------+---------+-------+
i was able to build this query to select all duplicate rows from multiple columns, according to this question
select t.*
from mytable t join
(select id, sub_id, spec_id, ex_time, count(*) as NumDuplicates
from mytable
group by sub_id, spec_id, ex_time
having NumDuplicates > 1
) tsum
on t.sub_id = tsum.sub_id and t.spec_id = tsum.spec_id and t.ex_time = tsum.ex_time
but now im not sure how to wrap this select with a delete query to delete the rows except for the ones with highest id.
as shown here
You can modify your sub-select query, to get maximum value of id for each duplication combination.
Now, while joining to the main table, simply put a condition that id value will not be equal to the maximum id value.
You can now Delete from this result-set.
Try the following:
DELETE t
FROM mytable AS t
JOIN
(SELECT MAX(id) as max_id,
sub_id,
spec_id,
ex_time,
COUNT(*) as NumDuplicates
FROM mytable
GROUP BY sub_id, spec_id, ex_time
HAVING NumDuplicates > 1
) AS tsum
ON t.sub_id = tsum.sub_id AND
t.spec_id = tsum.spec_id AND
t.ex_time = tsum.ex_time AND
t.id <> tsum.max_id
I am trying to optimize a query and I have it down to something like this,
select a.* from
(select id, count(oid) as cnt from stuff1 s1 inner join stuff2 s2 on s1.id=s2.id group by id) as a
right join
(select id,'0' as cnt from stuff2) as b
on a.id = b.id
Basically the goal was to get the count for each oid, where those having 0 count are also included. I had a query previous to this that worked fine but it took 30 seconds to execute. I am looking to optimize the old query with this one, but I am getting NULL values from table b. I need the values from table b to show up with id and 0. Any help would be greatly appreciated.
An example of the data set could be,
Stuff1
| oid | id |
|---- |----|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
Stuff2
| id |
|----|
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
the query should produce
| id | cnt |
|----|-----|
| 1 | 2 |
| 2 | 1 |
| 3 | 1 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
Your query is syntactically incorrect (oid may not be defined; id in the select is ambiguous). However, I suspect you want a simple left join:
select s2.id, count(s1.id) as cnt
from stuff2 s2 left join
stuff1 s1
on s1.id = s2.id
group by s2.id;
I was having problems in creating counting rows by grouping based on a given field value.
For example: I have a Table A structure like this:
+------+------------+
| id | Person |
+------+------------+
| 1 | "Sandy" |
| 2 | "Piper" |
| 3 | "Candy" |
| 4 | "Pendy" |
+------------+------+
Also I have a Table B structure like this:
+------+------------+---------+
| id | Person | Point |
+------+------------+---------+
| 1 | "Sandy" | 10 |
| 2 | "Piper" | 20 |
| 3 | "Candy" | 30 |
| 4 | "Sandy" | 10 |
| 5 | "Piper" | 20 |
| 6 | "Zafar" | 30 |
+------------+------+---------+
And needed a result like:
+------+------------+---------+
| id | Person | Point |
+------+------------+---------+
| 1 | "Piper" | 40 |
| 2 | "Candy" | 30 |
| 3 | "Zafar" | 30 |
| 4 | "Sandy" | 20 |
| 5 | "Pendy" | 0 |
+------------+------+---------+
I hope the table examples are itself self-explanatory.
SELECT person
, SUM(point) total
FROM
( SELECT person,point FROM table_b
UNION
ALL
SELECT person,0 FROM table_a
) x
GROUP
BY person
ORDER
BY total DESC;
It is a simple left join with a group by
select tableA.person, sum(tableB.points) from tableA left join tableB on tableA.person = tableB.person group by tableA.person
union
select tableB.person, sum(tableB.points) from tableB left join tableA on tableA.person = tableB.person where tableA.id is null group by tableA.person
I think below sql useful to you.
select a.id, a.Person,b.total_point from (
select id, Person from tablea) as a join
(select Person, sum(Point) as total_point from tableb group by person) as b on a.person =b.person
Thank you
How to select 1st, 2nd or 3rd value before MAX ?
usually we do it with order by and limit
SELECT * FROM table1
ORDER BY field1 DESC
LIMIT 2,1
but with my current query I don't know how to make it...
Sample table
+----+------+------+-------+
| id | name | type | count |
+----+------+------+-------+
| 1 | a | 1 | 2 |
| 2 | ab | 1 | 3 |
| 3 | abc | 1 | 1 |
| 4 | b | 2 | 7 |
| 5 | ba | 2 | 1 |
| 6 | cab | 3 | 9 |
+----+------+------+-------+
I'm taking name for each type with max count with this query
SELECT
`table1b`.`name`
FROM
(SELECT
`table1a`.`type`, MAX(`table1a`.`count`) AS `Count`
FROM
`table1` AS `table1a`
GROUP BY `table1a`.`type`) AS `table1a`
INNER JOIN
`table1` AS `table1b` ON (`table1b`.`type` = `table1a`.`type` AND `table1b`.`count` = `table1a`.`Count`)
and I want one more column additional to name with value before max(count)
so result should be
+------+------------+
| name | before_max |
+------+------------+
| ab | 2 |
| b | 1 |
| cab | NULL |
+------+------------+
Please ask if something isn't clear ;)
AS per your given table(test) structure, the query has to be as follows :
select max_name.name,before_max.count
from
(SELECT type,max(count) as max
FROM `test`
group by type) as type_max
join
(select type,name,count
from test
) as max_name on (type_max.type = max_name.type and count = type_max.max )
left join
(select type,count
from test as t1
where count != (select max(count) from test as t2 where t1.type = t2.type)
group by type
order by count desc) as before_max on(type_max.type = before_max .type)