Sure, see [http://dev.mysql.com/doc/refman/...tions.html#function_group-concat][1]:

    SELECT student_name,
      GROUP_CONCAT(DISTINCT test_score ORDER BY test_score DESC SEPARATOR &#39; &#39;)
      FROM student
      GROUP BY student_name;


  [1]: http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat

Do you mean to order by?

    SELECT _key,            
    COUNT(*) as cnt,            
    GROUP_CONCAT(_value ORDER BY _value SEPARATOR &#39;, &#39;) as value_list      
    FROM group_concat_test      
    GROUP BY _key      
    ORDER BY _key;

`UIView` has the properties `frame`, `bounds`, `center`, and `origin`, and they all seem to be interrelated.  Most of the time, I deal with `frame` when setting the position and size of a `UIView`.  I understand that `frame` is using global coordinate system and `bounds` is using coordinate of the local view (therefore its x and y are 0, but not always), but it&#39;s still confusing to me when to use what.

Under what context (and what&#39;s the right time) the other properties (`bounds`, `center`, `origin`) should be used?


UIView&#39;s frame, bounds, center, origin, when to use what?

I&#39;m trying to create a daemon in python. I&#39;ve found the [following question][1], which has some good resources in it which I am currently following, but I&#39;m curious as to why a double fork is necessary. I&#39;ve scratched around google and found plenty of resources declaring that one is necessary, but not why.

Some mention that it is to prevent the daemon from acquiring a controlling terminal. How would it do this without the second fork? What are the repercussions?

  [1]: https://stackoverflow.com/questions/473620/how-do-you-create-a-daemon-in-python

What is the reason for performing a double fork when creating a daemon?

In short: Is there any way to sort the values in a GROUP_CONCAT statement?

Query:

    GROUP_CONCAT((SELECT GROUP_CONCAT(parent.name SEPARATOR &quot; &amp;raquo; &quot;) 
    FROM test_competence AS node, test_competence AS parent 
    WHERE node.lft BETWEEN parent.lft AND parent.rgt 
      AND node.id = l.competence 
      AND parent.id != 1 
    ORDER BY parent.lft) SEPARATOR &quot;&lt;br /&gt;\n&quot;) AS competences
I get this row:

&gt; Crafts &amp;raquo; Joinery
&gt;
&gt; Administration &amp;raquo; Organization

I want it like this:
&gt; Administration &amp;raquo; Organization
&gt;
&gt; Crafts &amp;raquo; Joinery

MySQL: Sort GROUP_CONCAT values

In short: Is there any way to sort the values in a GROUP_CONCAT statement?
Query:
<pre><code class="hljs language-vbnet">GROUP_CONCAT((SELECT GROUP_CONCAT(parent.name SEPARATOR " &#x26;raquo; ") 
FROM test_competence AS node, test_competence AS parent 
WHERE node.lft BETWEEN parent.lft AND parent.rgt 
 AND node.id = l.competence 
 AND parent.id != 1 
ORDER BY parent.lft) SEPARATOR "&#x3C;br />\n") AS competences
</code></pre>
I get this row:
> Crafts » Joinery
>
> Administration » Organization
I want it like this:
> Administration » Organization
>
> Crafts » Joinery

Is something like this possible:

    SELECT DISTINCT COUNT(productId) WHERE keyword=&#39;$keyword&#39;

What I want is to get the number of unique product Ids which are associated with a keyword. The same product may be associated twice with a keyword, or more, but i would like only 1 time to be counted per product ID

Using DISTINCT and COUNT together in a MySQL Query

I currently have just under a million locations in a mysql database all with longitude and latitude information.

I am trying to find the distance between one point and many other points via a query. It&#39;s not as fast as I want it to be especially with 100+ hits a second.  

Is there a faster query or possibly a faster system other than mysql for this? I&#39;m using this query:

    SELECT 
      name, 
       ( 3959 * acos( cos( radians(42.290763) ) * cos( radians( locations.lat ) ) 
       * cos( radians(locations.lng) - radians(-71.35368)) + sin(radians(42.290763)) 
       * sin( radians(locations.lat)))) AS distance 
    FROM locations 
    WHERE active = 1 
    HAVING distance &lt; 10 
    ORDER BY distance;

_Note: The provided distance is in **Miles**. If you need **Kilometers**, use `6371 ` instead of `3959`._

Fastest Way to Find Distance Between Two Lat/Long Points

I&#39;m getting this strange error while processing a large number of data...

    Error Number: 1267
    
    Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation &#39;=&#39;
    
    SELECT COUNT(*) as num from keywords WHERE campaignId=&#39;12&#39; AND LCASE(keyword)=&#39;hello again &#230;˜” &#227;‹&#227;‚‰ &#227;‚&#227;‚‹ &#229; &#180;&#230;‰€&#39;

What can I do to resolve this? Can I escape the string somehow so this error wouldn&#39;t occur, or do I need to change my table encoding somehow, and if so, what should I change it to?

Illegal mix of collations MySQL Error

In another question I posted someone told me that there is a difference between:

    @variable

and:

    variable

in MySQL. He also mentioned how MSSQL has batch scope and MySQL has session scope. Can someone elaborate on this for me?

MySQL: @variable vs. variable. What&#39;s the difference?

I have a mysqldump backup of my mysql database consisting of all of our tables which is about 440 megs. I want to restore the contents of just one of the tables from the mysqldump. Is this possible? Theoretically, I could just cut out the section that rebuilds the table I want but I don&#39;t even know how to effectively edit a text document that size.

Can I restore a single table from a full mysql mysqldump file?

What&#39;s a fast way to sort a given set of images by their similarity to each other. 

At the moment I have a system that does histogram analysis between two images, but this is a very expensive operation and seems too overkill. 

Optimally I am looking for a algorithm that would give each image a score (for example a integer score, such as the RGB Average) and I can just sort by that score. Identical Scores or scores next to each other are possible duplicates.

    0299393
    0599483
    0499994 &lt;- possible dupe
    0499999 &lt;- possible dupe
    1002039
    4995994
    6004994 

RGB Average per image sucks, is there something similar?



Near-Duplicate Image Detection

I have a data with the following format:


    foo&lt;tab&gt;1.00&lt;space&gt;1.33&lt;space&gt;2.00&lt;tab&gt;3

Now I tried to sort the file based on the last field decreasingly.
I tried the following commands but it wasn&#39;t sorted as we expected.

    $ sort -k3nr file.txt  # apparently this sort by space as delimiter
    
    $ sort -t&quot;\t&quot; -k3nr file.txt
      sort: multi-character tab `\\t&#39;
    
    $ sort -t &quot;`/bin/echo &#39;\t&#39;`&quot; -k3,3nr file.txt
      sort: multi-character tab `\\t&#39;

What&#39;s the right way to do it?

Here is the [sample data][1].


  [1]: http://drop.io/hidden/5lmlo8s1th2eea/asset/ZmlsZS10eHQtZ3o= &quot;Sample Data&quot;

Sorting a tab delimited file

I need to take a C++ vector with potentially a lot of elements, erase duplicates, and sort it.

I currently have the below code, but it doesn&#39;t work.

    vec.erase(
          std::unique(vec.begin(), vec.end()),
          vec.end());
    std::sort(vec.begin(), vec.end());

How can I correctly do this?

Additionally, is it faster to erase the duplicates first (similar to coded above) or perform the sort first?  If I do perform the sort first, is it guaranteed to remain sorted after `std::unique` is executed?

Or is there another (perhaps more efficient) way to do all this?  


What&#39;s the most efficient way to erase duplicates and sort a vector?

I have a handful of records that I would like to sort based on a computed value. Got the answer [over here][1]... like so:

    sorted(Profile.objects.all(), key=lambda p: p.reputation)

on a Profile class like this:

    class Profile(models.Model):
        
        ...
        
        @property
        def reputation(self):
            ...

Unfortunately the generic view is expecting a queryset object and throws an error if I give it a list. 

**Is there a way to do this that returns a queryset**

or...

**Can I convert a list to a queryset somehow?** Couldn&#39;t find anything like that in the django docs.

I am hoping not to denormalize the data, but I guess I will if I have to.

Update / Answer:
==

it seems that the only way to get a queryset back is if you can get all of your logic into the sql queries. 

When that is not possible, (I think) you need to denormalize the data


  [1]: https://stackoverflow.com/questions/930865

django - convert a list back to a queryset

Trying to get the highest and lowest value from an array that I know will contain only integers seems to be harder than I thought.

&lt;!-- begin snippet: js hide: false console: true babel: false --&gt;

&lt;!-- language: lang-js --&gt;

    var numArray = [140000, 104, 99];
    numArray = numArray.sort();
    console.log(numArray)

&lt;!-- end snippet --&gt;

I&#39;d expect this to show `99, 104, 140000`. Instead it shows `104, 140000, 99`. So it seems the sort is handling the values as strings.

Is there a way to get the sort function to actually sort on integer value?


How to sort an array of integers correctly

I want to be able to select a bunch of rows from a table of e-mails and group them by the from sender.  My query looks like this:

    SELECT 
        `timestamp`, `fromEmail`, `subject`
    FROM `incomingEmails` 
    GROUP BY LOWER(`fromEmail`) 
    ORDER BY `timestamp` DESC

The query almost works as I want it — it selects records grouped by e-mail. The problem is that the subject and timestamp don&#39;t correspond to the most recent record for a particular e-mail address.

For example, it might return:

    fromEmail: john@example.com, subject: hello
    fromEmail: mark@example.com, subject: welcome

When the records in the database are:

    fromEmail: john@example.com, subject: hello
    fromEmail: john@example.com, subject: programming question
    fromEmail: mark@example.com, subject: welcome

If the &quot;programming question&quot; subject is the most recent, how can I get MySQL to select that record when grouping the e-mails?

MySQL &quot;Group By&quot; and &quot;Order By&quot;

I want my query to return the rows of the table where a column contains a specific value first, and then return the rest of the rows alphabetized.

If I have a table something like this example:

     - Table: Users
     - id - name -  city
     - 1    George  Seattle
     - 2    Sam     Miami
     - 3    John    New York
     - 4    Amy     New York
     - 5    Eric    Chicago
     - 6    Nick    New York

And using that table I want to my query to return the rows which contain New York first, and then the rest of the rows alphabetized by city. Is this possible to do using only one query?

How do I return rows with a specific value first?

I have a PHP array with numbers of ID&#39;s in it. These numbers are already ordered.

Now i would like to get my result via the IN() method, to get all of the ID&#39;s.

However, these ID&#39;s should be ordered like in the IN method.

For example:

    IN(4,7,3,8,9)  
Should give a result like:

    4 - Article 4  
    7 - Article 7  
    3 - Article 3  
    8 - Article 8  
    9 - Article 9

Any suggestions?  Maybe there is a function to do this?

Thanks!

MySQL ORDER BY IN()

I have a SQL table with a datetime field. The field in question can be null. I have a query and I want the results sorted ascendingly by the datetime field, however I want rows where the datetime field is null at the end of the list, not at the beginning.

Is there a simple way to accomplish that?

SQL how to make null values come last when sorting ascending

Can you please help me in solving this problem. I am trying to order the results of an SQL query by date, but I&#39;m not getting the results I need.

The query I&#39;m using is:

    SELECT date FROM tbemp ORDER BY date ASC


Results are:

    01/02/2009
    03/01/2009
    04/06/2009
    05/03/2009
    06/12/2008
    07/02/2009

Results should be:

    06/12/2008
    03/01/2009
    01/02/2009
    07/02/2009

I need to select the date in the format above. 

Your help is much appreciated.


SQL ORDER BY date problem

I have a query which uses the GROUP_CONCAT of mysql on an integer field.  
I am using PHPMYADMIN to develop this query. My problem that instead of showing 1,2 which is the result of the concatenated field, I get [BLOB - 3B].  

Query is

    SELECT rec_id,GROUP_CONCAT(user_id)
    FROM t1
    GROUP BY rec_id
(both fields are unsigned int, both are not unique)

What should I add to see the actual results?

using group_concat in PHPMYADMIN will show the result as [BLOB - 3B]

I have a table and I&#39;d like to pull one row per id with field values concatenated.

In my table, for example, I have this:

    TM67 | 4  | 32556
    TM67 | 9  | 98200
    TM67 | 72 | 22300
    TM99 | 2  | 23009
    TM99 | 3  | 11200

And I&#39;d like to output:

    TM67 | 4,9,72 | 32556,98200,22300
    TM99 | 2,3    | 23009,11200

In MySQL I was able to use the aggregate function `GROUP_CONCAT`, but that doesn&#39;t seem to work here... Is there an equivalent for PostgreSQL, or another way to accomplish this?

Postgresql GROUP_CONCAT equivalent?

I&#39;m using `GROUP_CONCAT()` in a MySQL query to convert multiple rows into a single string.
However, the maximum length of the result of this function is `1024` characters.

I&#39;m very well aware that I can change the param `group_concat_max_len` to increase this limit:

    SET SESSION group_concat_max_len = 1000000;

However, on the server I&#39;m using, I can&#39;t change any param. Not by using the preceding query and not by editing any configuration file.

So my question is:
Is there any other way to get the output of a multiple row query into a single string?

MySQL and GROUP_CONCAT() maximum length

I am doing `SELECT GROUP_CONCAT(categories SEPARATOR &#39; &#39;) FROM table`. Sample data below:

    categories
    ----------
    test1 test2 test3
    test4
    test1 test3
    test1 test3

However, I am getting `test1 test2 test3 test4 test1 test3` back and I would like to get `test1 test2 test3 test4` back. Any ideas?

Many thanks!

MySQL DISTINCT on a GROUP_CONCAT()

I&#39;m experiencing a problem with MySQL&#39;s &quot;GROUP_CONCAT&quot; function. I will illustrate my problem using a simple help desk database:

    CREATE TABLE Tickets (
     id INTEGER NOT NULL PRIMARY KEY,
     requester_name VARCHAR(255) NOT NULL,
     description TEXT NOT NULL);

    CREATE TABLE Solutions (
     id INTEGER NOT NULL PRIMARY KEY,
     ticket_id INTEGER NOT NULL,
     technician_name VARCHAR(255) NOT NULL,
     solution TEXT NOT NULL,
     FOREIGN KEY (ticket_id) REFERENCES Tickets.id);

    INSERT INTO Tickets VALUES(1, &#39;John Doe&#39;, &#39;My computer is not booting.&#39;);
    INSERT INTO Tickets VALUES(2, &#39;Jane Doe&#39;, &#39;My browser keeps crashing.&#39;);
    INSERT INTO Solutions VALUES(1, 1, &#39;Technician A&#39;, &#39;I tried to solve this but was unable to. I will pass this on to Technician B since he is more experienced than I am.&#39;);
    INSERT INTO Solutions VALUES(2, 1, &#39;Technician B&#39;, &#39;I reseated the RAM and that fixed the problem.&#39;);
    INSERT INTO Solutions VALUES(3, 2, &#39;Technician A&#39;, &#39;I was unable to figure this out. I will again pass this on to Technician B.&#39;);
    INSERT INTO Solutions VALUES(4, 2, &#39;Technician B&#39;, &#39;I re-installed the browser and that fixed the problem.&#39;);

Notice that this help desk database has two tickets, each with two solution entries. My goal is to use a SELECT statement to create a list of all of the tickets in the database with their corrosponding solution entries. This is the SELECT statement I&#39;m using:

    SELECT Tickets.*, GROUP_CONCAT(Solutions.solution) AS CombinedSolutions
    FROM Tickets
    LEFT JOIN Solutions ON Tickets.id = Solutions.ticket_id
    ORDER BY Tickets.id;

The problem with the above SELECT statement is it&#39;s returning only one row:

    id: 1
    requester_name: John Doe
    description: My computer is not booting.
    CombinedSolutions: I tried to solve this but was unable to. I will pass this on to Technician B since he is more experienced than I am.,I reseated the RAM and that fixed the problem.,I was unable to figure this out. I will again pass this on to Technician B.,I re-installed the browser and that fixed the problem.

Notice that it&#39;s returning ticket 1&#39;s information with both ticket 1&#39;s and ticket 2&#39;s solution entries.

What am I doing wrong? Thanks!

Content Type	Original Author	Original Content on Stackoverflow
Question	Ivar	View Question on Stackoverflow
Solution 1 - Mysql	Sampson	View Answer on Stackoverflow
Solution 2 - Mysql	Haim Evgi	View Answer on Stackoverflow

MySQL: Sort GROUP_CONCAT values

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

What is the reason for performing a double fork when creating a daemon?

UIView's frame, bounds, center, origin, when to use what?

Attributions