GROUP BY : SQL Aggregation for Common Values

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How do I add an alias to the table

SELECT MAX(COUNT), A.id FROM ( SELECT supplier_id as id, COUNT(*) AS count FROM `library`.`lms_book_details` GROUP BY supplier_id ) GROUP BY A.id; While executing the query, MySQL gives ...
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1answer
29 views

Grouped Data tracking [closed]

I have a MS Access Database that tracks clients, client regions and transaction types. Users are keying in transactions and once done, the system needs to create letters to the client regions ...
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1answer
44 views

Group by reversible pair

I'm sure my title is not clear enough... Let's say I have a "chat" table, storing individual messages like this: message_id, from_user_id, to_user_id, timestamp For a given user_id, I want a list ...
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3answers
123 views

How to query for 'First showed up as'

Given the following table: Date Trd (INT(10)) Code (VARCHAR(10)) T-Date 1-Jan-14 1 B 1-Nov-13 1-Jan-14 2 B 3-Oct-13 ...
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0answers
122 views

Select Foo object without any specific Bar events

Consider two tables: Foo: id INT, name VARCHAR Bar: id INT, foo_id INT REFERENCES Foo(id), event_type VARCHAR DEFAULT NULL, event_duration INT DEFAULT NULL Each Foo item can have ...
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1answer
42 views

SELECT showing two COUNTs

I had this table: tblA id | name | value 1 nameA 1 2 nameA 0 3 nameB 0 4 nameC 0 5 nameC 1 6 nameC 1 As you see, Value can be 1 or 0 I need to perform a query ...
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1answer
99 views

How to remove duplicates in col1 and get group MAX in col2? / mysql

Given the following table: col1 Col2 A 1 B 1 C 1 B 2 B 3 A 0 C 5 how do I write a SELECT query (I just assumed has to be SELECT) that returns the unique items of col1 and the ...
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1answer
140 views

How to UPDATE MAX and MIN of a GROUP BY?

I have a SELECT query of a table with GROUP BY id col1 category 1 some 1 2 x 1 3 another 1 4 x 2 // should be removed 5 some 2 6 x ...
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4answers
2k views

Select rows based on latest date with multiple joins

I have this query (SQLFiddle): SELECT c.name, a.user_id, a.status_id, a.title, a.rtime, u.user_name, s.status_name FROM company c LEFT JOIN action a ON a.company_id=c.id LEFT JOIN user u ON ...
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1answer
367 views

Get max date for each year from list of dates

Need to get max date for each year from list of arbitrary dates: date year ================= 1/10/2013 2013 3/26/2013 2013 4/20/2012 2012 9/10/2012 2012 5/6/2011 2011 So ...
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0answers
65 views

is it good to add index on column used in group by clause?

I have a query like- select x, sum(y) from xyz where z>=100 group by x order by sum(y) desc; will it be faster if I am going to add index on x?
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2answers
97 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 ...
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2answers
2k 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
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2answers
2k 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 ...
3
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1answer
886 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 ...
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0answers
237 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 ...
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0answers
80 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 ...
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2answers
194 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 ...
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1answer
280 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
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2answers
121 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
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1answer
62 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, ...
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2answers
41 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; ...
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0answers
87 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 ...
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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. ...
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0answers
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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, ...
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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 ...
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1answer
7k 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
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1answer
310 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 ...
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2answers
538 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
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1answer
338 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
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1answer
211 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
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1answer
509 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 ...
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2answers
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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 ...
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2answers
217 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
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2answers
163 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
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2answers
165 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, ...
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1answer
3k 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 ...
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1answer
111 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 ...
1
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1answer
3k 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 ...
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4answers
463 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
2k 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 ...
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6answers
3k 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 ...
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1answer
971 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 ...
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1answer
170 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
750 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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3answers
992 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 ...
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1answer
591 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
552 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 , ...
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1answer
6k 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 ...
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1answer
397 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 ...