GROUP BY : SQL Aggregation for Common Values

learn more… | top users | synonyms

1
vote
2answers
112 views

Duplicates while doing multiple joins

I have 4 MySQL tables 1. companies - {id*, company} 2. employees - {id*, fname, lname, id_company*} 3. technologies - {id*, technology} 4. company_technologies - {id_technology*, id_company*} Field ...
4
votes
2answers
4k views

SQL join query to show rows with non-existent rows in one table

I am trying to get some reporting done for employee time records. We have two tables specifically for this question. Employees are listed in the Members table and each day they enter time entries of ...
4
votes
2answers
3k views

GROUP BY with MAX versus just MAX

I am a programmer, dealing with a big table which the following scheme: UpdateTime, PK, datetime, notnull Name, PK, char(14), notnull TheData, float There is a clustered index on Name, UpdateTime ...
4
votes
1answer
2k views

Can column name be “Group” in Postgresql or in any databases

I was designing a project which specifies that in a table what column name should be and one of the column name in the specification is "group". I tried creating it but it always throw a syntax ...
5
votes
2answers
363 views

Should I group by and then join, or join and then group by?

(oracle's optimizer does the same thing for both approaches when just two tables are involved, thus my question involves three tables) Assume three tables t1, t2 and t3 with a pairwise 1:n ...
0
votes
0answers
96 views

can this mysql query be optimized further?

I have this query select counterparty_id, max(id) max_id from client_administrations where counterparty_type = 1 and effective_on <= '2013-10-22' group by counterparty_id When I ...
3
votes
2answers
308 views

How do I use window functions (“over”) together with crosstab in Postgres?

Table: application_app applied_date | applied_class | id -------------------------------+---------------+----- 2013-03-06 15:59:49.22774-05 | BOSFAL13 | 13 2013-05-12 ...
0
votes
1answer
421 views

Column 'Comments.Text' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause

They have explained the root of the problem very well and even advised to use max aggregate as a solution. But, lets take the example group_id item_id comment -------------------------------- ...
2
votes
2answers
126 views

Optimize query or model, to get an population overview in time

I think I've got a very simple model and query, but I cannot find a way to make use of indexes to boost performance. I wonder if there is a trick in my model, or MySQL query, to speed up the ...
1
vote
1answer
63 views

Do id columns help (in speed) select statements?

I have a table which contains data from aggregation software. The columns mostly are int columns, but three of them are string columns. It looks sort of like: userId, someData1, someData2, ...
0
votes
2answers
42 views

Calculating the number of times a group occures

I'm trying to figure out how many times in my database a particular grouping has occurred. I have two relevant tables. mysql> describe logins; ...
1
vote
0answers
122 views

How to index for a group by with columns from different tables?

Is it possible to create an index from columns of 2 different tables? If not, how do we optimize a query that does a group by on columns of 2 different tables? For example: the following ...
0
votes
1answer
43 views

SELECT to only see Offsetting Transactions in table?

I have a temp table like this I have been playing with it but I don't know how to get same PortCode,Cusip combo to give me only offsetting transactions (Buy,Sells) not (Purchase,Purchase) combos. ...
0
votes
0answers
42 views

Ranking MySQL, group by, with ties [duplicate]

I am trying to rank some MySQL results and this works quite well (from here): SET @rank := 0; SET @prev := NULL; UPDATE rankings, (SELECT @rank := IF(@prev = subset, @rank + 1, 1) AS rank, ...
1
vote
1answer
55 views

MySQL Grouping Order

Is it possible to force the order in which a result set is grouped? I have a table with multiple languages in it, and I'm doing a GROUP_CONCAT to get a comma separated list of the product name in each ...
-2
votes
1answer
13k views

How to get MAX and MIN in GROUP BY query?

In a simple query SELECT col1, col2, col3 FROM table1 GROUP BY col1 each row includes the first value of col2 and col3 for each unique value of col. How to select MAX and MIN for each value of ...
2
votes
1answer
437 views

Grouping over multiple data dimensions (pivot)

I am logging an Events table, and want an output (as seen at the bottom of this answer), the issue is that I am getting the data in rows, but want them to be displayed column-wise. The two dimensions ...
1
vote
2answers
686 views

Avoiding a sort on an already clustered index for group by

On a table T with two fields, pid and did, the following query results in a seq. scan followed by a sort on pid: select count(did), pid from T group by pid Here is the query plan: ...
3
votes
1answer
428 views

Group By primary key or DISTINCT increase query time over 1000x with limit

Also see http://stackoverflow.com/questions/17741167/hibernate-jpa-improve-performance-of-distinct-query but I realized this is mainly a PostgreSQL issue. My application uses a 3rd party extension to ...
0
votes
1answer
304 views

Need to find the number of employee who are not in all department

i have a table T1 which has two columns empname , department every emp must be in 37 department , but there are some employee who are in less than 37 department . I need to find the names of emp who ...
2
votes
1answer
673 views

Is it possible to reduce a group to a row based on some criteria?

I'd like to perform a select on a table involving a GROUP BY such that all rows that share the same set of identifiers are grouped together, but I want to reduce the group to one of the grouped rows ...
0
votes
2answers
4k views

How to use GROUP BY after the Having clause Mysql

Here is the query which gets the accounts for a specific user the products are related to accounts in one-to-many relation so for each product there are four permissions All the accounts which is not ...
2
votes
2answers
270 views

Why does adding LIMIT to my query make it crawl?

Simple query: select sum(score) total,name,gender,dob,country from users join scores on users.id = scores.user_id where date between '2012-01-01' and '2012-01-31 23:59:59' group by scores.user_id ...
1
vote
2answers
205 views

Group Database Entries by time difference

I have a large postgreSQL database with log data. All this data has timestamps and I want to group consecutive rows where the difference between the timestamps is less then 1500 miliseconds for ...
2
votes
2answers
183 views

Repeated values in group_concat

I have two tables, first the table food and Second is Activity: INSERT INTO food (`id`, `foodName`) VALUES (1, 'food1'), (2, 'food2'), (3, 'food3'), (4, 'food4'), (5, ...
0
votes
1answer
4k views

WITH ROLLUP WHERE x IS NULL

I tried to find this question somewhere else on here, and found a couple that were similar to it -- but all the answers seemed pretty convoluted, and I think it was surprising to me because I just ...
1
vote
1answer
184 views

GROUP BY with OR/AND clause?

Lets say my database looks like this: Table: messages +----+------+----+----------+----------+ | id | from | to | double_1 | double_2 | +----+------+----+----------+----------+ | 1 | 1 ...
2
votes
1answer
4k views

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 ...
2
votes
4answers
603 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 ...
4
votes
2answers
3k views

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 ...
8
votes
6answers
4k views

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 ...
1
vote
1answer
2k views

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 ...
1
vote
1answer
200 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 ...
2
votes
2answers
1k 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` ...
3
votes
3answers
1k views

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 ...
0
votes
1answer
845 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 ...
5
votes
2answers
792 views

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 , ...
2
votes
1answer
8k views

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 ...
1
vote
1answer
464 views

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 ...
0
votes
1answer
392 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, ...
4
votes
2answers
7k 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 ...
4
votes
4answers
5k 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 ...
3
votes
1answer
259 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 ...
6
votes
1answer
308 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 ...
4
votes
2answers
500 views

MySQL check duplicate with group by using wildcard?

+----+--------------+-----+-----------+----------+ | ID | NAME | AGE | ADDRESS | SALARY | +----+--------------+-----+-----------+----------+ | 1 | Ramesh Olive | 32 | ...
1
vote
2answers
8k views

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 | ...
3
votes
2answers
6k 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(*) ...
0
votes
1answer
6k views

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 ...
5
votes
1answer
168 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 ...
1
vote
1answer
2k views

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, ...