I have table like this one:
I would like to all rows, but if there is user_id 5 if this case, override other rows which have no user_id.
I tried both with MAX(user_id) and GROUP BY country_name, but it still returns, wrong results.
Final result I'm expecting:
Try this;)
select t1.*
from yourtable t1
inner join (
select max(user_id) as user_id, country_name from yourtable group by country_name
) t2 on t1.country_name = t2.country_name and t1.user_id = t2.user_id
This is just a solution based on your sample data. If you have a variety of user_id, it should be more different.
As of SQL Select only rows with Max Value on a Column you can easily get rows with max value on a column by using both MAX(column) and GROUP BY other_column in one statement.
But if you want to select other columns too, you have to this in a subquery like in the following example:
SELECT a.*
FROM YourTable a
INNER JOIN (
SELECT country_name, MAX(user_id) user_id
FROM YourTable
GROUP BY country_name
) b ON a.country_name = b.country_name AND a.user_id = b.user_id
Related
I don't know if my title is understandable or not, may be someone can help edit my title?
All I want to do is, for example:
I have a table like this
Engineering appears 5 times with different article_category_abbr, and I want to select only one row with the biggest value of num.
Here, it will be Engineering-ENG-192, and Geriatrics&Gerontology will be Geriatrics&Gerontology-CLM-26
But I don't know how to do it on the whole table using mysql
Join your table to a subquery which finds the greatest num value for each sc group.
SELECT t1.*
FROM yourTable t1
INNER JOIN
(
SELECT sc, MAX(num) AS max_num
FROM yourTable
GROUP BY sc
) t2
ON t1.sc = t2.sc AND
t1.num = t2.max_num;
You can have a subquery that gets the largest value for each sc and the resulting rows will then be joined with the table itself based from two columns - sc and num.
SELECT a.*
FROM tableName a
INNER JOIN
(
SELECT sc, MAX(num) AS Num
FROM tableName
GROUP BY sc
) b ON a.sc = b.sc
AND a.num = b.num
Here's a Demo
USE MAX function and GROUP BY like this. Here is more information.
SELECT myID, classTitle, subField, MAX(score) FROM myTable GROUP BY myID, classTitle, subField
I wanna run a subquery that uses the value of the outer query in its where clause. Here's and example of what I wanna do:
SELECT * FROM `tbl1`
WHERE `tbl1`.`max_count` < (
SELECT COUNT(*) rc FROM `tbl2`
WHERE `tbl2`.`id` = `tbl1`.`id
)
There is tbl1 with a column named max_count, and there is tbl2 with rows referring to a row in tbl1(many-to-one relationship). What I wanna do is select rows in tbl1 where the number of rows in tbl2 referencing it is less than the max_count value of that row. But I'm pretty sure that what I wrote here, ain't gonna cut it. Any ideas?
Thanks a lot
try this -
SELECT * FROM `tbl1` t1
WHERE t1.`max_count` < (
SELECT COUNT(*) FROM `tbl2` t2
WHERE t2.`id` = t1.`id`
)
try using JOIN.
SELECT DISTINCT a.*
FROM tb1 a
INNER JOIN
(
SELECT id, COUNT(*) totalCount
FROM tbl2
GROUP BY id
) b ON a.ID = b.ID
WHERE a.max_count < b.totalCount
As an alternate solution, it's probably easier to just use a LEFT JOIN with HAVING than a subquery;
SELECT tbl1.*, COUNT(tbl2.id) current_count
FROM tbl1
LEFT JOIN tbl2
ON tbl1.id=tbl2.id
GROUP BY tbl1.id
HAVING COUNT(tbl2.id) < max_count
An SQLfiddle to test with.
Note that the GROUP BY in this case is a MySQL only thing, normally you'd need to GROUP BY every selected field in tbl1 even if tbl1.id is known to be unique per row.
I have a mysql query. I need to get last value from columns Lat,Lng from my table but serial_number column needs to be distinct.
How to make such a query?
This is needed as I am using this coordinates to load it to Google map. So when the Google maps loads I need to have a marker on each last coordinates where vehicle is.
SELECT m.*
FROM (
SELECT DISTINCT serial_number
FROM mytable
) md
JOIN mytable m
ON m.id =
(
SELECT id
FROM mytable mi
WHERE mi.serial_number = md.serial_number
ORDER BY
mi.time DESC, mi.id DESC
LIMIT 1
)
Create an index on (serial_number, time, id) for this to work fast.
If you want to retrieve the last record for a certain serial_number, just use this:
SELECT *
FROM mytable
WHERE serial_number = :my_serial_number
ORDER BY
time DESC, id DESC
LIMIT 1
1#
Assuming that max ID will always give you last lat and lon, the query becomes quite simple -
SELECT t2.*
FROM table t2
where t2.id IN
(
SELECT max(t1.id)
FROM table t1
GROUP BY t1.serial_number
)
2#
If you need to consider time also, then you will need to do it this way. Here, in the inner query, max_time of each serial_number is obtained. Then this max_time and serial_number is joined with the outer table time and serial_number respectively, to get distinct records with last lat and lon.
SELECT *
FROM table t2,
(
SELECT max(t1.time) max_time, t1.serial_number
FROM table t1
GROUP BY t1.serial_number
) new_table
WHERE t2.time=new_table.max_time
AND t2.serial_number=new_table.serial_number
Try this
select distinct serial_number, *
from table t
inner join table t1 on t1.serial_number = t.serial_number and t1.id = (select max id from table t2 where t2.serial_number = t1.serial_number)
i have table as
id----name----roll-----class
1----ram-------1-----2
2----shyam-----2-----3
3----ram-------1-----3
4----shyam-----2-----3
5----ram-------1-----2
6----hari------1-----5
i need to find the the duplicate row only that have common name, roll, class. so the expected result for me is.
id----name----roll-----class
1----ram-------1-------2
2----shyam-----2-------3
4----shyam-----2-------3
5----ram-------1-------2
i tried to get from the query below but here only one field is supported. i need all three field common. Please do help me in this. thanks
SELECT *
FROM table
WHERE tablefield IN (
SELECT tablefield
FROM table
GROUP BY tablefield
HAVING (COUNT(tablefield ) > 1)
)
You can use count() over().
select id, name, roll, class
from (select id, name, roll, class,
count(*) over(partition by name, roll, class) as c
from YourTable) as T
where c > 1
order by id
https://data.stackexchange.com/stackoverflow/query/63720/duplicates
this will retun only the duplicate entry one time:
select t.id, t.name, t.roll, t.class
from table t
inner join table t1
on t.id<t1.id
and t.name=t1.name
and t.roll = t1.roll
and t.class=t1.class
this will return what you require:
select distinct t.id, t.name, t.roll, t.class
from table t
inner join table t1
on t.name=t1.name
and t.roll = t1.roll
and t.class=t1.class
I'd suggest something like this
SELECT A.* FROM
Table A LEFT OUTER JOIN Table B
ON A.Id <> B.Id AND A.Name = B.Name AND A.Roll = B.Roll AND A.Class = B.Class
WHERE B.Id IS NOT NULL
Something like that should work (I did not test though):
select a1.*
from table a1, a2
where (a1.id != a2.id)
and (a1.name == a2.name)
and (a1.roll== a2.roll)
and (a1.class== a2.class);
It seems there are several proprosals here. If it is a query that you'll use in your code, beware of the cost of the queries. Try an 'explain' with your database.
I have a table as follows:
ident_nr|proj_nr|start_time|
----------------------------
05.26.73|0000001|1116936920|
09.56.df|0000002|1213431234|
11.ac.12|0000003|1236485758|
98.er.df|0000001|1287789755|
70.12.5n|0000001|1011245554|
33.dt.vp|0000003|1239125544|
And I want a result like this:
ident_nr|proj_nr|start_time|
----------------------------
98.er.df|0000001|1287789755|
09.56.df|0000002|1213431234|
33.dt.vp|0000003|1239125544|
where proj_nr is in asc order and start time with the max value.
Note: ident_nr is unique and proj_nr could have multiple ident_nr.
Database: MySQL.
Is there an SQL query that could achieve this result?
Thanks
SELECT t.ident_nr, t.proj_nr, t.start_time
FROM YourTable t
INNER JOIN (SELECT proj_nr, MAX(start_time) AS MaxTime
FROM YourTable
GROUP BY proj_nr) q
ON t.proj_nr = q.proj_nr
AND t.start_time = q.MaxTime
ORDER BY t.proj_nr;
SELECT t1.*
FROM table AS t1
INNER JOIN (
SELECT proj_nr, MAX(start_time) AS MaxTime
FROM table
GROUP BY proj_nr) AS t2
ON (t1.proj_nr = t2.proj_nr AND t1.start_time = t2.MaxTime)
Your criteria seems to be MAX(start_time) in your sample data. If not, please be more detailed in your question about what you want.