2
votes
1answer
23 views

Making MySQL use primary index without hinting or forcing

I have the following db structure: CREATE TABLE `question` ( `id` int(11) NOT NULL AUTO_INCREMENT, `level_id` int(11) NOT NULL, `video_id` int(11) NOT NULL, `is_active` tinyint(1) NOT NULL, ...
0
votes
0answers
20 views

Mysql Show records according to their positions by grouping and order by

I am writing a query i should show the records according to the rank position given along with price order and group by sitename shopdetails id | productid | productname | sitename | siteid | ...
1
vote
1answer
29 views

cant order NULL value properly (mysql)

So I got this view in mysql : CREATE VIEW vote_question_totals AS SELECT question_id , SUM((vote_question_type)='1') question_total_plus , SUM((vote_question_type)='-1') question_total_minus , ...
0
votes
0answers
70 views

group by and order by making query very slow in mysql?

Query works fast: select SQL_NO_CACHE users.id, users.name from useres left join user_statistics on users.id = user_statistics.user_id where users.is_deleted = 0 group by users.id ...
1
vote
1answer
30 views

Am I using the ORDER BY clause incorrectly

I am trying to enumerate a database, created specifically for the purpose of learning SQL injections. I am trying to discover the number of columns a particular select statement might be using. I do ...
0
votes
2answers
37 views

Sorting of results is slow some times but fast at other times

I have a mysql query that is joining a few tables and then uses order by field for sorting. It sometimes runs quite fast at other times it is slow. While it was slow i profiled the query to find that ...
1
vote
2answers
128 views

MySQL: Is it possible to order a query by a specific letter using ORDER BY?

What I'd like to do is order my query so that the results show every row found, but are ordered by showing results that begin with the letter 'D' first. Is this something that is possible to do with ...
0
votes
0answers
30 views

Which of these two queries is better - can be optimized more?

With regards to the usage of the IF statement, which is better to use? Query #1: SELECT whatever FROM auctions AS a LEFT JOIN ............... WHERE ............... ORDER BY ...
0
votes
1answer
41 views

Order result by number of occurence of a word in a text

I am working with sqlite3/python . I would like to order results by the number of occurence of %@% in text. For exemple Jimmy 10 // Jimmy wrote 10 strings like %@% James 2 Sophia 0 ..etc The ...
1
vote
1answer
71 views

increment row value does not work properly with where condition

I have created sql fiddle as below it is working fine if i remove where condition(WHERE rg.groupid= 1) output without where condition | ID | RANK | MYORDER | PREVIOUSRANK | ...
0
votes
3answers
890 views

Running an “ORDER BY CASE” query on MySQL view breaks it afterwards

Whenever I create a MySQL view and then run a query ordering the results with ORDER BY CASE WHEN (...), the view becomes unusable. The newly created view works properly and all SQL is correct. This ...
0
votes
1answer
29 views

Sorting by a field in child table

There are two tables: contract (with primary key contractid) and contractupdate (with field contractid referring to a contract). contractupdate also has DATE field startdate and TINYINT field day. I ...
0
votes
2answers
78 views

Filesort while using primary key for orderby

I have been breaking my head for the past two days now for this. CREATE TABLE `clients` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `guarantor_name` varchar(50) NOT NULL, ...
0
votes
0answers
162 views

Using an enum as part of an index definition

When I use an ENUM column in a table the ORDER BY uses the ordinal of the ENUM not its value. I wasn't aware of that. So my question is what are the subtle issues when an ENUM is part of an index ...
0
votes
2answers
48 views

same field in bothe “where” and “order by” - how to index for this query?

The query: EXPLAIN EXTENDED SELECT *, u.user_id FROM xgate_geoloc g JOIN tig_users u ON g.uid = u.uid WHERE -- corners selection: ( ( ...
0
votes
0answers
99 views

Slow query with ORDER BY with index created (more than 4mins on 0.6million records

I ran into a very weird query performance situation. If I run this query without order by, it finish in millsecs, with order by, it ends up with more than 4mins. EXPLAIN SELECT `book_book`.`id`, ...
0
votes
1answer
241 views

Getting MySQL User Variable in Sequence, While Using ORDER BY RAND()

I am running a SELECT statement, which ultimately will be in an INSERT..SELECT statement. I want a result like this ID COUNTER 3 1 7 2 1 3 20 4 12 ...
0
votes
1answer
39 views

Extract data for all groups in a single SELECT statement

MySQL 5. Table: schedule Columns: id int(10) UN PK AI startdate date groupid smallint(5) UN The following statement extracts the Schedule ID for a given group (the schedule with the latest date ...
0
votes
1answer
60 views

How to arrange rows selected in MYSQL query?

I'm fetching data from a table "TABLE_A", it's having Primary Key as "PK_ONE" (which is unsigned INT) . I'm fetching data from "TABLE_A" with where clause on PK_ONE ; Ex: SELECT PK_ONE from TABLE_A ...
2
votes
2answers
2k views

MySQL not using indexes when joining against another table

I have two tables, the first table contains all articles / blog posts within a CMS. Some of these articles may also appear in a magazine, in which case they have a foreign key relationship with ...
0
votes
1answer
171 views

Index for ORDER BY on aggregate in MySQL

I'm working with the following query: SELECT *, SUM(entries_count) AS entries_count FROM leads WHERE promo_id IN (1, 2, 3) GROUP BY user_id ORDER BY entries_count DESC LIMIT 25 OFFSET 100; It's ...
0
votes
1answer
1k views

SQL Limit + count group?

I'm tracking all the visitors of my site using this table: Visitors table In my admin panel, I have an overview of which countries visited my site, where they came from, ..., but because over 20+ ...
1
vote
1answer
52 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 ...
0
votes
1answer
387 views

How can I join two tables while filtering the results with a“ WHERE IN” clause? [closed]

What I am trying to do is set up a selection filter for a cascading list on my site. When I say selection filter, I mean I am trying to limit, and sort the results based on what the user selects. I ...
1
vote
4answers
423 views

MySql Order by isnull() Performance Problem

my sql below is use for listing stock added from 10 days ago. Order by isnull(Price) is use so that stock without any price yet will still being listed. AddDate and Price has an index. SELECT Id, ...
1
vote
1answer
64 views

ORDER BY optimization issue

I have a query: SELECT user_details.id , user_details.first_name , user_details.last_name, user_accounts.name account_name, jtl0.account_id account_id, user_details.title , ...
2
votes
1answer
557 views

Why is MySQL order by performance poor within a single partition of a partitioned table?

I have to store some sequence numbered data in MySQL. I have about 300,000 data items per day for about a 10 year span. Let's say the table structure is just sequence number (a big int) and data (a ...
0
votes
1answer
49 views

Index on a query with order

I have the following table with >1M rows: CREATE TABLE `wishlist_place` ( `id` int(11) NOT NULL AUTO_INCREMENT, `wishlist_id` int(11) DEFAULT NULL, `place_id` int(11) DEFAULT NULL, `city_id` ...
0
votes
1answer
487 views

Optimizing ORDER BY for simple MySQL query

I'm trying to optimize this really simple query, and it gives me grief for a day now :( Seems pretty straightforward, I need to select with a JOIN from 2 tables, and get top X results sorted in a ...
1
vote
2answers
40 views

Order by on an alphanumerical column

I have a column that has strings of the following type: Miller 10 Allen 20 King 10 .... Jones 100 I try to sort the column based on the numerical part of the data. I tried the following: SELECT ...
0
votes
1answer
404 views

Mysql: order by field or select union?

As a newbie, I expected Mysql to return the rows of this query ordered by their ids order in the id clause select * from test where id in (3,1,2) Unfortunatelly for me, that's not true. The results ...
2
votes
1answer
778 views

Update one table from another table while sorting that table based on one column

This is the problem I'm trying to figure out in MySQL. We have an old table contains some forms submitted by our users. Somehow, the previous decision was each time a user comes to this survey, a new ...
3
votes
1answer
94 views

Sequential joining of tables in order

Table albums has (among other field) field id. Table photos has column id, field album which is a foreign key referring to album id and some other fields (which are irrelevant for the question I ...
2
votes
2answers
558 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` ...
8
votes
2answers
978 views

Must an index cover all selected columns for it to be used for ORDER BY?

Over at SO, someone recently asked Why isn't ORDER BY using the index? The situation involved a simple InnoDB table in MySQL comprising three columns and 10k rows. One of the columns, an integer, ...
1
vote
1answer
854 views

MySql: #1221 - Incorrect usage of UNION and ORDER BY

I have the following query which is intended to retrieve the newest 3 comments for each post in an array of posts. SELECT * FROM comment AS tbl WHERE sscm_id IN ( SELECT sscm_id FROM comment AS t1 ...
2
votes
2answers
611 views

MySQL order by - one column conditional on another column

In MySQL I have a table (simplified for this question) CREATE TABLE `projects` ( `id` int(11) NOT NULL AUTO_INCREMENT, `title` varchar(255) NOT NULL, `priority` int(11) DEFAULT '1000000', ...
1
vote
1answer
187 views

GROUP_CONCAT with ORDER BY , but results are not ordered

The following query works fine SELECT *, (SELECT GROUP_CONCAT(url SEPARATOR '$$' ) FROM project_photos WHERE project_id = projects.id ORDER BY priority) AS images FROM projects WHERE catID = 2 LIMIT ...
1
vote
1answer
1k 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, ...
3
votes
1answer
5k views

MySQL: Optimize UNION with “ORDER BY” in inner queries

I just set up a logging system which consists of multiple tables with the same layout. There is one table for each data source. For the log viewer, I want to UNION all the log tables, filter them ...
1
vote
0answers
245 views

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 ...
0
votes
1answer
56 views

Is index like key(timetime) usable when we query: SELECT * … ORDER BY timetime DESC

When we index a timestamp field like timetime. Can we use it for ORDER BY timetime DESC or is it just usable for ORDER BY timetime ASC OR ORDER BY timetime? Does mySQL use this index when doing vise ...
1
vote
1answer
66 views

How to order by 5, 501, 50101, 6, 601, 60101, etc?

I've got a list of ledger account numbers. These numbers go like this: 5 (main account, #5) 501 (sub account of main account 5, #01) 50101 (sub account of this account, #01) etc. So if I have a ...
3
votes
1answer
594 views

How to order query results by tag weight in IN('tag1', 'tag2', 'tag3')

Consider a simple query as SELECT * FROM posts JOIN tags USING(post_id) JOIN tag_map USING(tag_id) WHERE tags.tag IN('tag1', 'tag2', 'tag3') tag_map is a many-to-many relationship between tables ...
3
votes
3answers
500 views

MySQL: ORDER BY useless?

CREATE TEMPORARY TABLE tt; INSERT INTO tt; many times SELECT FROM tt ORDER BY id LIMIT ?,1000; The temp table is created at the beginning of the script having an "id" auto_increment column (and ...
3
votes
2answers
3k views

MySql: Delete all rows greater than n entries ordered by datetime

Can someone help me with a MySql query to delete all rows greater than n entries ordered by date? I.e. say I have 1200 rows of data with a timestamp column. I need to order it by date and preserve ...
10
votes
1answer
5k views

Order by column should have index or not?

I have added indexes to table which are used for searching result. I am showing results by ASC or DESC order. So that column should have index or not? I have 2 more indexes on that table. How ...
1
vote
1answer
1k views

Help optimizing MySQL slow query

i'm running a wordpress which needs some mysql optimization, i have a slow query and i would like to get rid of "Using temporary; Using filesort" query: EXPLAIN SELECT SQL_CALC_FOUND_ROWS wp_posts.* ...
2
votes
3answers
153 views

Ordering by date and other columns

I have a one table Q&A like below: CREATE TABLE `totaalconceptterreinonderhoud`.`acties` ( `id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID', `type` int(11) NOT NULL DEFAULT '3' ...
3
votes
4answers
2k views

MySQL : Conditional ORDER BY to only one column

Hello and thanks for taking time to read this question. I am using MySQL, and I want to sort results using ORDER BY to one specific column, but the results must be ordered according an specific ...