GROUP BY : SQL Aggregation for Common Values

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1answer
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Error “column does not exist” in a SELECT with JOIN and GROUP BY query

I'm using PostgreSQL 9.1 with a Ruby on Rails application. I'm trying to list the last version of each "charge" (in my history table : hist_version_charges) belonging to the same project id ...
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4answers
511 views

Delete the N oldest entries grouped by multiple columns

I´d like to delete the oldest entries of my database, but in each category shall remain at least N words of each char. Structure of TABLE words id | word | char | category For example I have the ...
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2answers
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Postgres: Use result of group by as column names

I have a messages table in a database, which include a sender id and a message type (and of course many more columns not relevant for this question). I try to create a query which counts how many ...
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Find “n” consecutive free numbers from table

I have some table with numbers like this (status is either FREE or ASSIGNED) id_set number status ----------------------- 1 000001 ASSIGNED 1 000002 FREE 1 000003 ...
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postgres GROUP BY and ORDER BY problem

I have two tables like this: CREATE TABLE cmap5 ( name VARCHAR(2000), lexemes TSQUERY ); and CREATE TABLE IF NOT EXISTS synonyms_all_gin_tsvcolumn ( cid int NOT NULL ...
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1answer
181 views

Avoiding performance hit from GROUP BY during FULLTEXT search?

Is there any clever way to avoid the performance hit from using group by during fulltext search? SELECT p.topic_id, min(p.post_id) FROM forum_posts AS p WHERE MATCH (p.post_text) AGAINST ('baby ...
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2answers
902 views

Slow MySQL query with Order and Group by

I have a query that is taking a long time to execute (1.13s). The two tables user_articles and articles have around 25,000 records. This is the query: SELECT `user_articles`.* FROM `user_articles` ...
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PostgreSQL 8.3: Slow GROUP BY on large table

I have a table with about 10 million records. I want to do a simple group by, but it's using a sequential scan and is slow... select run_id, count(*) from result group by run_id; I have an index ...
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1answer
688 views

Group By on column from joined table

its about the following query. EXPLAIN SELECT phrase, infinitiv FROM `dict_verbs_all` `t` INNER JOIN `dict_verbs_all_language` `verbsGerman_c` ON (`t`.`id`=`verbsGerman_c`.`verb_id`) INNER JOIN ...
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2answers
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T-SQL Purpose of MAX in this Group By Query

I have run into some pre-existing SQL that I'm having a hard time uderstanding. SELECT MAX(I.Symbol) Symbol , MAX(I.Ticker) CUSIP , MAX(I.Name) Name , SUM(H.Quantity) TotalQuantity , ...
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1answer
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Multiple “GROUP_CONCAT”s with WHERE clause

In a table as id name type info 1 BMW car yes 2 Reno car no 3 IBM electronics no 4 Sony electronics yes 5 Mazda ...
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1answer
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Select Count(*) FROM with-clause-named table order by a, b not working

I have a series of tables defined in a stored procedure to eventually return to the application like this, then culminating to a simple table which contains distinct values from a previously defined ...
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1answer
313 views

Group By - Incorrect syntax near 'mycolumn' [closed]

I'm getting a syntax error in SQL Server Management Studio (SQL Server 2008) for the following query: SELECT MIN(EffectiveOn) AS EffectiveOn, Address1, Address2, Address3, ...
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2answers
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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 ...
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4answers
4k views

Slow query on large table with GROUP BY and ORDER BY

I have a table with 7.2 million tuples which looks like this: table public.methods column | type | attributes ...
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1answer
246 views

SELECT multiple sensor values in one query

Background I have a couple of devices, each with a couple of sensors. I log these every now and then and stores them in a table described below. When someone requests a web page, I fetch a couple of ...
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1answer
299 views

What corner cases exist when relying on undocumented behaviour to determine values selected by MySQL for hidden columns in GROUP BY operations?

Under GROUP BY and HAVING with Hidden Columns, the MySQL manual documents (added emphasis): MySQL extends the use of GROUP BY so that the select list can refer to nonaggregated columns not named ...
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2answers
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MySQL check duplicate with group by using wildcard?

+----+--------------+-----+-----------+----------+ | ID | NAME | AGE | ADDRESS | SALARY | +----+--------------+-----+-----------+----------+ | 1 | Ramesh Olive | 32 | ...
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2answers
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how to calculate difference of first row and last row fields value in each group

I have table with structure like this: +-------+------------------+ | Value | Date | +-------+------------------+ | 10 | 10/10/2010 10:00 | | 11 | 10/10/2010 10:15 | | 15 | ...
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2answers
5k views

GROUP BY two columns

I want to count two columns, but need to get the results of first column in one row. SELECT country, COUNT(*) FROM table1 GROUP BY country, type This query gives me country type COUNT(*) ...
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1answer
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Need to count records and group count by date on Oracle

I have a table like the following ID created sent type ----------------------------------------------------- 0001463583000051783 31-JUL-12 1 270 0081289563000051788 ...
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1answer
148 views

GROUP BY on a dependent field

Let's say I have a SELECT statement as follows: SELECT ..., field1 FROM ... GROUP BY field1 Now let's say I want to return a second field, field2. As it happens, field2 is functionally dependent ...
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1answer
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Slow complex query with group/order

I have a problem with a very important query in my application. It is very slow when adding group and order to it. So the full query is: SELECT m.id, m.title, m.title_text, ...
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2answers
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Grouping data checking against top values

I've got data in this form: CallNum Value Accepted -------------------------------------- 971374 81.482204444473609 True 971374 83.783551111089764 False 971374 97.936875555547886 ...
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2answers
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Pivoting data for stacked charts (grouping and creating new columns for each distinct value)?

I have something that looks like this (SQL Fiddle here): Date Location Value 1/1/2012 Baltimore 36 1/1/2012 Houston 36 1/1/2012 Chicago 55 2/1/2012 Baltimore 49 ...
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2answers
715 views

limit and then group by in MySQL

I have a mysql table having following structure : payment_id(int auto_increment), emp_id(int), chargeTime(datetime), payment(double) I need to have three latest (with respect to chargeTime) ...
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0answers
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MySQL GROUP BY and ORDER BY giving inconsistent results

I'm currently working with WordPress, and I've added a new meta value which is a number between 0 and 30. Zero is ignored and up to 30 need to be organised in order and only the latest (based on the ...
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2answers
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Why do wildcards in GROUP BY statements not work?

I am trying to make the following SQL statement work, but I get a syntax error: SELECT A.*, COUNT(B.foo) FROM TABLE1 A LEFT JOIN TABLE2 B ON A.PKey = B.FKey GROUP BY A.* Here, A is a wide table ...