I am trying to select the latest entry of the duplicate entries against the ticket_id in a mysql table , My current is something like this.
SELECT * ,
COUNT(*) AS cnt ,
ticket_id
FROM temp_tickets
GROUP BY ticket_id
ORDER BY id DESC
It gives the number of times a row is duplicated but i am able to select the latest one of those mulptiple rows
Let say i have 3 ticket_id's which got duplicated for 5 times so now i want to select the latest occurrence from all these 3 id's .
Lemme know if i have to be more specific.
Thanks
Here's one way (assuming "latest" means "greatest id")
SELECT temp_tickets.*
FROM temp_tickets
JOIN ( SELECT MAX(id) AS id
FROM temp_tickets
GROUP BY ticket_id
HAVING COUNT(*) > 1
) latest ON latest.id = temp_tickets.id
I suspect it might be possible to come up with a more efficient solution involving user variables but I'll leave that to someone else...
Related
right now I'm trying to return the biggest COUNT(DISTINCT column)-number from a mysql table.
It's hard to describe, so I'll give you an example:
My table has the following columns: s_id, k_id, p_id.
Now I want to count the different s with the condition that every entry has the same p_id, too. I need this to prepare a HTML-Table (so i know how many Columns this table will have).
Data Example:
This is what I got, so far:
SELECT COUNT(DISTINCT k_id) AS a FROM `table`
the problem with this is, that there may be 4 different k_ids but 3 of them are related to p_id = 1 and the last one is releated to p_id = 2.
a returns 4 instead of 3.
Thanks for support!
I think you want this:
select p_id, count(distinct s_id) as cnt
from table
group by p_id
order by cnt desc
limit 1;
Please consider this:
select max(count(distinct(k_id))) from table
group by p_id
I have read many replies and to similar questions but cannot seem to apply it to my situation. I have a table that averages 10,000 records and is ever changing. It containing a column called deviceID which has about 20 unique values, another called dateAndTime and many others including status1 and status2. I need to isolate one instance each deviceID, showing the record that had the most current dateAndTime. This works great using:
select DISTINCT deviceID, MAX(dateAndTime)
from MyTable
Group By deviceID
ORDER BY MAX(dateAndTime) DESC
(I have noticed omitting DISTINCT from the above statement also yields the same result)
However, I cannot expand this statement to include the fields status fields without incurring errors in the statement or incorrect results. I have tried using IN and EXISTS and syntax to isolate rows, all without luck. I am wondering how I can nest or re-write this query so that the results will display the unique deviceID's, the date of the most recent record and the corresponding status fields associated with those unique records.
If you can guarantee that the DeviceID + DateAndTime is UNIQUE you can do the following:
SELECT *
FROM
MyTable as T1,
(SELECT DeviceID, max(DateAndTime) as mx FROM MyTable group by DeviceID) as T2
WHERE
T1.DeviceID = T2.DeviceID AND
T1.DateAndTime = T2.mx
So basically what happens is, that you do a group by on the DeviceID (NOTE: A GROUP BY always goes with an aggregate function. We are using MAX in this case).
Then you join the Query with the Table, and add the DeviceID + DateAndTime in the WHERE clause.
Side Note... GROUP BY will return distinct elements with or without adding DISTINCT because all rows are distinct by default.
Maybe:
SELECT a.*
FROM( SELECT DISTINCT *,
ROW_NUMBER() OVER (PARTITION BY deviceID ORDER BY dateAndTime DESC) as rown
FROM MyTable ) a
WHERE a.rown = 1
Sometimes I want to get just one row of each similar value, I ussually do somethingl ike this:
SELECT * GROUP BY Text ORDER BY Date DESC
My problem using GROUP to select similar rows is that I don't get the values from the latest rows in the row (I'm not quite sure what's the criteria to choosing the row that stays). I want to retain only the newest row in the group.
I know how to do it with a self join but when statements are already very long it seems a bit complicated. Is there any shorter method? Maybe using DISTINCT instead of GROUP BY?
Assuming you have a table that has multiple columns and two of which are GroupID and DATE. If you want to select the latest record for each GroupID, you need to have a subquery which gets the latest Date for each GroupID, example
SELECT a.* -- this just selects all records from original table
FROM tableName a
INNER JOIN
(
-- this subquery gets the latest DATE entry for each GROUPID
SELECT GroupID, MAX(DATE) maxDate
FROM tableName
GROUP BY GroupID
) b ON a.GroupID = b.GroupID AND
a.Date = b.maxDate
if this answer is not clear, please do ask :D
Did you try to use the max function:
SELECT A,B,max(Date) GROUP BY Text
I'm currently using the following query (simplified indeed) :
SELECT
(
SELECT COUNT(id)
FROM bla_1
WHERE id NOT IN (SELECT id FROM blahhh)
)
+
(
SELECT COUNT(id)
FROM bla_2
WHERE id NOT IN (SELECT id FROM blahhh)
)
as count
Before somebody mentions it, may i add bla_1 and bla_2 don't contain the same data, even if with that simplified query it might seem so.
The problem here is that some ids counted by the second query are already taken care of by the first one. In other words, the second query could return '2', and one of those 2 counted rows would already be counted by the first query.
So, since both queries have some ids in common that i don't want to count twice, i came up with that :
SELECT
(
SELECT COUNT(id)
FROM bla_1
WHERE id NOT IN (SELECT id FROM blahhh)
)
+
(
SELECT COUNT(id)
FROM bla_2
WHERE id NOT IN (SELECT id FROM blahhh)
AND id NOT IN (SELECT id
FROM bla_1
WHERE id NOT IN (SELECT id FROM blahhh)
)
)
as count
You will notice that the second subquery inside the second query is the exact same query as the first one.
My problem is that i can't get to make this work without executing the same query twice (a first time to count results, and a second time to actually retrieve those results).
Much love to the one solving that problem :-)
Try using the UNION operation that will eliminate duplicates for you.
SELECT COUNT(ID) AS MyCount
FROM
( SELECT ID FROM Table1 WHERE /*....*/
UNION
SELECT ID FROM Table2 WHERE /*....*/
) r
I am trying to select of the duplicate rows in mysql table it's working fine for me but the problem is that it is not letting me select all the fields in that query , just letting me select the field name i used as distinct , lemme write the query for better understading
mysql_query("SELECT DISTINCT ticket_id FROM temp_tickets ORDER BY ticket_id")
mysql_query("SELECT * , DISTINCT ticket_id FROM temp_tickets ORDER BY ticket_id")
1st one is working fine
now when i am trying to select all fields i am ending up with errors
i am trying to select the latest of the duplicates let say ticket_id 127 is 3 times on row id 7,8,9 so i want to select it once with the latest entry that would be 9 in this case and this applies on all the rest of the ticket_id's
Any idea
thanks
DISTINCT is not a function that applies only to some columns. It's a query modifier that applies to all columns in the select-list.
That is, DISTINCT reduces rows only if all columns are identical to the columns of another row.
DISTINCT must follow immediately after SELECT (along with other query modifiers, like SQL_CALC_FOUND_ROWS). Then following the query modifiers, you can list columns.
RIGHT: SELECT DISTINCT foo, ticket_id FROM table...
Output a row for each distinct pairing of values across ticket_id and foo.
WRONG: SELECT foo, DISTINCT ticket_id FROM table...
If there are three distinct values of ticket_id, would this return only three rows? What if there are six distinct values of foo? Which three values of the six possible values of foo should be output?
It's ambiguous as written.
Are you looking for "SELECT * FROM temp_tickets GROUP BY ticket_id ORDER BY ticket_id ?
UPDATE
SELECT t.*
FROM
(SELECT ticket_id, MAX(id) as id FROM temp_tickets GROUP BY ticket_id) a
INNER JOIN temp_tickets t ON (t.id = a.id)
You can use group by instead of distinct. Because when you use distinct, you'll get struggle to select all values from table. Unlike when you use group by, you can get distinct values and also all fields in table.
You can use DISTINCT like that
mysql_query("SELECT DISTINCT(ticket_id), column1, column2, column3
FROM temp_tickets
ORDER BY ticket_id");
use a subselect:
http://forums.asp.net/t/1470093.aspx