Use this for problems that involve returning one or more rows from each group in a data set. Despite the name, this tag is suitable for *minimum-* and *maximum-* per group queries.

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4
votes
2answers
28 views

PostgreSQL Get top-k minimum per range

Assume I have the following data: | f1 | f2 | f3 | |----|----|----| | 1 | 1 | 1 | | 1 | 1 | 5 | | 1 | 2 | 3 | | 1 | 2 | 6 | | 1 | 3 | 4 | | 1 | 3 | 7 | | 2 | 1 | 2 | | 2 | 1 | ...
1
vote
2answers
226 views

Adding a 'last time occurred' flag column

I need to add a column into a table that contains 3 columns: GroupKey - Shows the number of an item. Status - the number of the status that the group was according the insert date. The status ...
2
votes
1answer
20 views

Selecting closest, non expired value [duplicate]

I'm trying to select multiple rows where the value is closest to the end date but not passed, and return only those rows. Here's a sample of some data: School Code | School Year | Semester | Term | ...
5
votes
2answers
117 views

Nested aggregation and grouping on multiple columns in MySQL

Consider the following product table (which is highly trimmed down): `id` int AUTO_INCREMENT `category_id` int `subcategory_id` int `vendor_id` int `price` decimal(6,2) `inserted_at` timestamp For ...
2
votes
1answer
97 views

select n values per group

Lets say I have the following table ----------------------------- | user_id | comment | ----------------------------- | 2 | thats cool | | 2 | awesome | | 3 ...
1
vote
2answers
93 views

Minimum value on most recent date per account MS ACCESS SQL

I have a MS ACCESS DB table Riskscore with the three fields: CHACCTBS, CHRQDATE, CHSCORE and want to find the lowest CHSCORE on the most recent CHRQDATE per CHACCTBS where it is possible to have ...
1
vote
3answers
168 views

Remove duplicate values from query result

I am using Postgres 9.3.9. I have 2 tables : f_agent : CREATE TABLE f_agent ( f_agent__id bigserial NOT NULL, f_agent__total_users integer NOT NULL, f_agent__dim_time_id integer NOT NULL, ...
3
votes
3answers
46 views

How to select a row based on the maximum value of a column, when ties are expected

SUBSCRIBER DATE TIME VALUE aaa 23-04-2015 04:04:07 10 aab 23-04-2015 12:04:32 5 bbb 23-04-2015 01:04:05 20 bbb 23-04-2015 ...
1
vote
4answers
116 views

How to select first row from a join that returns multple rows on the primary key

This is related to this question: Joining multiple tables results in duplicate rows I have two tables that I am joining. They share a key. The person table has one name per primary key but the ...
0
votes
1answer
159 views

Is it possible to select distinct values in a json document using PostgreSQL?

I have a column that is using the JSON type. I would like to perform a query to select all distinct records for a particular field in the JSON string: I.e. given these three documents { id: 1, s: ...
0
votes
1answer
37 views

mysql Quiz leaderboard filter by points, time taken

I have a quiz report table which shows a report for every quiz a user takes. I need to create a leaderboard from this, which shows the top users best score, filtering by points and then time taken. ...
3
votes
1answer
107 views

How to index for timestamp queries

I have a products table where I insert around 150,000 records a day. Most of them are redundant, but I need to keep them because of the new expiration date. I get product feeds from about 5 vendors a ...
1
vote
4answers
79 views

Getting an aggregate (here: min) for a group of values [closed]

Example table: ID | value A | value B ---------------------- 1 | abc | 3 1 | def | 5 1 | ghi | 1 2 | cba | 9 2 | fed | 4 I want the ...
0
votes
1answer
62 views

Select records as groups based on sequence and date

I have data stored as: CompID | Seq | Udate | Utime --------+-----+-----------+------- mx433 | 1 | 1/1/2012 | 13:54 mx433 | 1 | 1/2/2012 | 13:43 mx433 | 2 | 1/4/2012 | 14:23 mx433 ...
0
votes
2answers
65 views

Speed up SELECT with WINDOW, (PARTITION … ORDER) with compound index

I have the following table: CREATE TABLE ranking_points ( id serial NOT NULL, store_id integer, book_id integer, list_name character varying(255), rank integer, created_at timestamp ...
0
votes
1answer
108 views

What is the best query to get the latest row version based on time?

I'm wondering what can be the most efficient query to get the latest rows from the following table. CREATE TABLE AGE_DATA ( INSERTED_DAY TIMESTAMP(6), HOSTNAME VARCHAR2(255 CHAR), CONCEPT ...
2
votes
3answers
143 views

Aggregate query with min

Having a product_stock table with following structure: product_id warehouse_id stock price Which has bunch of records (same product can be in different warehouses): 1, 1, 0, 500 1, 2, 5, 505 1, 3, ...
4
votes
1answer
351 views

Subselect of MAX(Version) takes many minutes, though there are only ~20K records

I have a pretty complicated data model. I can't understand most SQL examples without an explanation of what's being modeled, so I'll try to explain. Mainlines -> Releases -> Overlays -> Calibrations ...
1
vote
1answer
68 views

Select all most recent records

I have this two tables (and their main fields): Target: Message: Id IdMessage Id IdMain IdReply DatePosted ================ ...
1
vote
2answers
126 views

Efficient query to get last row group by multiple columns

I have a table like the following: spread_id serial NOT NULL, game_id integer NOT NULL, sportsbook_id integer NOT NULL, spread_type integer NOT NULL, spread_duration integer NOT NULL, home_line ...
3
votes
2answers
72 views

Selecting minimum value in top grouping only

I have a query built in Oracle 10 which produces a set of data like this: EMP_ID WORK_DT TIME_TYPE ---------- --------- --------- 12345 19-DEC-14 10 12345 18-DEC-14 10 ...
1
vote
1answer
98 views

How to Select the First (or last) entry for a specific day

I have a table "AttendanceRecords" with entries like this EntryID UUID PRIMARY KEY, StafID UUID REFERENCES staffmembers(ID) NOT NULL, ArrivalTime TIMESTAMP NOT NULL, DepartureTime TIMESTAMP For one ...
39
votes
6answers
3k views

Retrieving n rows per group

I often need to select a number of rows from each group in a result set. For example, I might want to list the 'n' highest or lowest recent order values per customer. In more complex cases, the ...
0
votes
2answers
2k views

How to select top 10 records from each category [duplicate]

I have a table with fields Hour, PathId, Duration, Event, CellId, Channel I have 50+ CellId. Each CellId has four PathId (i.e. 0, 1, 2, 3). Each PathId has many Events and Durations. Now I want to ...
0
votes
1answer
33 views

Query with column data for a max

In Postgres, I have a table like this: Column | Type | Modifiers ...
0
votes
2answers
72 views

Find the last visit by teacher and show the rest of columns in MySql

I would like to group the teachers by the last visit and show the other values corresponding to the last visit. CREATE TABLE IF NOT EXISTS `visits` ( `FIELD1` int(5) NOT NULL, `teacher` varchar(9) ...
0
votes
3answers
153 views

Get latest status of an item in the database

I have this table: ID|Item-FK |timestamp|status ============================= 1 | 123 | ... | OK 2 | 123 | ... | FAILED ... I want to query get all items which last status was FAILED. ...
2
votes
2answers
4k views

Join 3 tables and return only distinct values for max datetime

I've been trying to do this the whole 2 weeks but seems like to no avail. 3 tables involved here. but am expecting the result would be distinct case no. for the same date & user. otherwise, it ...
2
votes
1answer
108 views

Selecting most recent date when dates are stored in another table

Working in a MySQL database, I have tables set up like this: Table song_instances has song_id (int), meeting_instance_id (int) The meeting_instances table has columns meeting_instance_id (int), ...
0
votes
1answer
131 views

Select latest record for each ID

I have three tables that contains data as below: Users Id Name Other_Columns --------------------------- 1 John Blah 2 Ricky Blah 3 Stella Blah 4 Bob Blah Saldo Id ...
4
votes
3answers
6k views

GROUP BY one column, while sorting by another in PostgreSQL

How can I GROUP BY one column, while sorting only by another. I'm trying to do the following: SELECT dbId,retreivalTime FROM FileItems WHERE sourceSite='something' GROUP BY seriesName ...
3
votes
2answers
1k views

Are ORDER BY clause & ROW_NUMBER duplicating functionality when I need top n queries

I have a table that tracks violations for a student. I want to count the number of violations and select top 2 violators from each class. The query would look like this SELECT * FROM ( SELECT ...
2
votes
1answer
128 views

Why am I getting different results from a query vs. a view

The base problem I'm facing is that I need the latest record for each item. A little setup... MySQL 5.6.14. I need to create two views (because MySQL won't let me have a subquery in a view). My ...
0
votes
1answer
91 views

group by and display contents of last row for each result

I've got some data of two objects and I want to retrieve the last row of both the objects, preferably in one query. Table structure: CREATE TABLE data ( pid serial NOT NULL, dt timestamp without ...
4
votes
2answers
475 views

select specified number of unique IDs where second column is unique

Look at the following example starting from the top row (id=9) and work your way down, selecting a limit of 4 rows that have sec's that we have not yet seen. We "select" id=9 because we don't yet have ...
1
vote
1answer
58 views

Consolidating large table

I need some help with a complex query. Table def: Table "public.agent_log" Column | Type | Modifiers ...
3
votes
1answer
435 views

Find the second highest value from a subquery or derived table

I have a subquery which returns the following results. 'c003', '120000.00' 'c002', '90000.00' 'c001', '20000.00' 'c005', '8000.00' 'c004', '5000.00' I want to find the second highest value from ...
1
vote
2answers
294 views

optimization of expensive subquery

The following query gets the last report (where latitude and longitude and secs are <> 0) associated with the specified units: SELECT reports.* FROM reports INNER JOIN ...
1
vote
2answers
78 views

Nearest value for each foreign key

I have a table with a primary key, timestamp, value, foreign key. I would like to find the nearest value to a timestamp for each of the foreign keys in a list. Unfortunately, the gap from the given ...
2
votes
2answers
301 views

UPDATE table with another table data

I want to update the table car_check field fencing.(total 40 rows).I also use postgis function. I think it's a little difficult.Any suggestions? The code is the first carid example. UPDATE car_check ...
9
votes
2answers
11k views

Efficient query to get greatest value per group from big table

Given the table: Column | Type id | integer latitude | numeric(9,6) longitude | numeric(9,6) ...
28
votes
6answers
42k views

How do I efficiently get “the most recent corresponding row”?

I have a query pattern that must be very common, but I don't know how to write an efficient query for it. I want to look up the rows of a table that correspond to "the most recent date not after" the ...
1
vote
2answers
67k views

Select which has max date or latest date

Here are two tables. SCHOOL_STAFF SCHOOL_CODE + STAFF_TYPE_NAME + LAST_UPDATE_DATE_TIME + PERSON_ID ================================================================= ABE Principal ...
4
votes
2answers
10k views

How group with min(date) and select an another column in the same table

I have a query who return something like it : Name Gender Job date of hire John M mechanic 2012-05-08 John M electrician 2010-01-01 Vicky F scientific 2012-11-11 Bob ...
18
votes
5answers
83k views

How to select the first row of each group?

I have a table like this: ID | Val | Kind ---------------------- 1 | 1337 | 2 2 | 1337 | 1 3 | 3 | 4 4 | 3 | 4 I want to make a SELECT that will return just the ...