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  • MySQL: SELECT highest column value when WHERE finds similar entries

    - by Ike
    My question is comparable to this one, but not quite the same. I have a database with a huge amount of books, with different editions of some of the same book titles. I'm looking for an SQL statement giving me the highest edition number of each of the titles I'm selecting with a WHERE clause (to find specific book series). Here's what the table looks like: |id|title |edition|year| |--|-------------------------|-------|----| |01|Serie One Title One |1 |2007| |02|Serie One Title One |2 |2008| |03|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |05|Serie One Title Three |1 |2008| |06|Serie One Title Three |2 |2009| |07|Serie One Title Three |3 |2010| |08|Serie One Title Three |4 |2011| |--|-------------------------|-------|----| The result I'm looking for is this: |id|title |edition|year| |--|-------------------------|-------|----| |03|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |08|Serie One Title Three |4 |2011| |--|-------------------------|-------|----| The closest I got was using this statement: select id, title, max(edition), max(year) from books where title like "serie one%" group by name; but it returns the highest edition and year and includes the first id it finds: |--|-----------------------|-------|----| |01|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |05|Serie One Title Three |4 |2011| |--|-----------------------|-------|----| This fancy join also comes close, but doesn't give the right result: select b.id, b.title, b.edition, b.year from books b inner join (select name, max(edition) as maxedition from books group by title) g on b.edition = g.maxedition where b.title like "serie one%" group by title; Using this I'm getting unique titles, but mostly old editions.

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  • Test the sequentiality of a column with a single SQL query

    - by LauriE
    Hey, I have a table that contains sets of sequential datasets, like that: ID set_ID some_column n 1 'set-1' 'aaaaaaaaaa' 1 2 'set-1' 'bbbbbbbbbb' 2 3 'set-1' 'cccccccccc' 3 4 'set-2' 'dddddddddd' 1 5 'set-2' 'eeeeeeeeee' 2 6 'set-3' 'ffffffffff' 2 7 'set-3' 'gggggggggg' 1 At the end of a transaction that makes several types of modifications to those rows, I would like to ensure that within a single set, all the values of "n" are still sequential (rollback otherwise). They do not need to be in the same order according to the PK, just sequential, like 1-2-3 or 3-1-2, but not like 1-3-4. Due to the fact that there might be thousands of rows within a single set I would prefer to do it in the db to avoid the overhead of fetching the data just for verification after making some small changes. Also there is the issue of concurrency. The way locking in InnoDB (repeatable read) works (as I understand) is that if I have an index on "n" then InnoDB also locks the "gaps" between values. If I combine set_ID and n to a single index, would that eliminate the problem of phantom rows appearing? Looks to me like a common problem. Any brilliant ideas? Thanks! Note: using MySQL + InnoDB

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  • Unique constraint with nullable column

    - by Álvaro G. Vicario
    I have a table that holds nested categories. I want to avoid duplicate names on same-level items (i.e., categories with same parent). I've come with this: CREATE TABLE `category` ( `category_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `category_name` varchar(100) NOT NULL, `parent_id` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`category_id`), UNIQUE KEY `category_name_UNIQUE` (`category_name`,`parent_id`), KEY `fk_category_category1` (`parent_id`,`category_id`), CONSTRAINT `fk_category_category1` FOREIGN KEY (`parent_id`) REFERENCES `category` (`category_id`) ON DELETE SET NULL ON UPDATE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish_ci Unluckily, category_name_UNIQUE does not enforce my rule for root level categories (those where parent_id is NULL). Is there a reasonable workaround?

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  • Why MySQL multiple-column index is overpopulated?

    - by actual
    Consider following MySQL table: CREATE TABLE `log` ( `what` enum('add', 'edit', 'remove') CHARACTER SET ascii COLLATE ascii_bin NOT NULL, `with` int(10) unsigned NOT NULL, KEY `with_what` (`with`,`what`) ) ENGINE=InnoDB; INSERT INTO `log` (`what`, `with`) VALUES ('add', 1), ('edit', 1), ('add', 2), ('remove', 2); As I understand, with_what index must have 2 unique entries on its first with level and 3 unique entries in what "subindex". But MySQL reports 4 unique entries for each level. In other words, number of unique elements for each level is always equal to number of rows in log table. Is that a bug, a feature or my misunderstanding?

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  • jQgrid: multiple column row headers

    - by Jonathan
    I am trying to extend my jQGrid to have multiple rows for the header. It will look something like this ----------------------- Level 1 - > | Application | ----------------------- Level 2 - > |Code | Name | ----------------------- | 0002827| Mobile Phone1 | 0202827| Mobile Phone2 | 0042827| Mobile Phon3e | 0005827| Mobile Phone4 | 0002627| Mobile Phon5e | 0002877| Mobile Phone6 | 0002828| Mobile Phone7 I am wondering how to do this with jQGrid 3.8.2? Any ideas?

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  • how to get particular column distinct in linq to sql

    - by kart
    Hi All, Am having columns as category and songs in my table for each category there are almost 10 songs and in total there are 7 category such that which was tabled as category1 songCategory1a category1 songCategory1b category1 songCategory1c --- category2 songCategory2a category2 songCategory2b category2 songCategory2c --- category3 songCategory3a category3 songCategory3b category3 songCategory3c --- like that there is table in that i want to get the result as category1 category2 category3 category4 kindly any one help me , i tried (from s in _context.db_songs select new { s.Song_Name, s.Song_Category }).Distinct().ToList(); but it didnt work its resulting as such.

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  • ndarray field names for both row and column?

    - by Graham Mitchell
    I'm a computer science teacher trying to create a little gradebook for myself using NumPy. But I think it would make my code easier to write if I could create an ndarray that uses field names for both the rows and columns. Here's what I've got so far: import numpy as np num_stud = 23 num_assign = 2 grades = np.zeros(num_stud, dtype=[('assign 1','i2'), ('assign 2','i2')]) #etc gv = grades.view(dtype='i2').reshape(num_stud,num_assign) So, if my first student gets a 97 on 'assign 1', I can write either of: grades[0]['assign 1'] = 97 gv[0][0] = 97 Also, I can do the following: np.mean( grades['assign 1'] ) # class average for assignment 1 np.sum( gv[0] ) # total points for student 1 This all works. But what I can't figure out how to do is use a student id number to refer to a particular student (assume that two of my students have student ids as shown): grades['123456']['assign 2'] = 95 grades['314159']['assign 2'] = 83 ...or maybe create a second view with the different field names? np.sum( gview2['314159'] ) # total points for the student with the given id I know that I could create a dict mapping student ids to indices, but that seems fragile and crufty, and I'm hoping there's a better way than: id2i = { '123456': 0, '314159': 1 } np.sum( gv[ id2i['314159'] ] ) I'm also willing to re-architect things if there's a cleaner design. I'm new to NumPy, and I haven't written much code yet, so starting over isn't out of the question if I'm Doing It Wrong. I am going to be needing to sum all the assignment points for over a hundred students once a day, as well as run standard deviations and other stats. Plus, I'll be waiting on the results, so I'd like it to run in only a couple of seconds. Thanks in advance for any suggestions.

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  • Sqllite doesn' write a column

    - by user1904675
    I do this: DatabaseHelper dbHelper = new DatabaseHelper(context); dbHelper.getWritableDatabase(); String sql = "insert into "+getTableName()+("+DatabaseHelper.PRODUCT_MARK+","+DatabaseHelper.PRODUCT_NAME+") VALUES ('"+input.getMark()+"','"+input.getName()+"')"; System.out.println(sql); getDatabase().execSQL(sql); dbHelper.close(); The system print 12-14 16:53:33.857: I/System.out(1350): insert into product (pMark,name) VALUES ('aaaaa ','zz') But when I read from db the property mark is not valorized... Where is my mistake?

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  • rails 3 how to automatically post user_id in column of comments

    - by user568502
    hi, im totally new to rails. here my question: i made an app with articles and comments and use devise for authentication sadly im only able to post 1 hyperlink so this is the middle part of my post with the files at gist: https://gist.github.com/771366 the article_id is pre selected in the comments/_form - but the user_id isnt. i googled a lot, tried value = session[:user_id] and others, but nothing worked would be great if someone could tell me how it works ^^ thx

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  • Dynamic where clause in LINQ - with column names available at runtime

    - by sandesh247
    Disclaimer: I've solved the problem using Expressions from System.Linq.Expressions, but I'm still looking for a better/easier way. Consider the following situation : var query = from c in db.Customers where (c.ContactFirstName.Contains("BlackListed") || c.ContactLastName.Contains("BlackListed") || c.Address.Contains("BlackListed")) select c; The columns/attributes that need to be checked against the blacklisted term are only available to me at runtime. How do I generate this dynamic where clause? An additional complication is that the Queryable collection (db.Customers above) is typed to a Queryable of the base class of 'Customer' (say 'Person'), and therefore writing c.Address as above is not an option.

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  • mysql get table based on common column between two tables

    - by Zentdayn
    while trying to learn sql i came across "Learn SQL The Hard Way" and i started reading it. Everything was going fine then i thought ,as a way to practice, to make something like given example in the book (example consists in 3 tables pet,person,person_pet and the person_pet table 'links' pets to their owners). I made this: report table +----+-------------+ | id | content | +----+-------------+ | 1 | bank robbery| | 2 | invalid | | 3 | cat on tree | +----+-------------+ notes table +-----------+--------------------+ | report_id | content | +-----------+--------------------+ | 1 | they had guns | | 3 | cat was saved | +-----------+--------------------+ wanted result +-----------+--------------------+---------------+ | report_id | report_content | report_notes | +-----------+--------------------+---------------+ | 1 | bank robbery | they had guns | | 2 | invalid | null or '' | | 3 | cat on tree | cat was saved | +-----------+--------------------+---------------+ I tried a few combinations but no success. My first thought was SELECT report.id,report.content AS report_content,note.content AS note_content FROM report,note WHERE report.id = note.report_id but this only returns the ones that have a match (would not return the invalid report). after this i tried adding IF conditions but i just made it worse. My question is, is this something i will figure out after getting past basic sql or can this be done in simple way? Anyway i would appreciate any help, i pretty much lost with this. Thank you. EDIT: i have looked into related questions but havent yet found one that solves my problem. I probably need to look into other statements such as join or something to sort this out.

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  • incrementing a table column's data by one || mySql

    - by Praveen Prasad
    iam having a table with columns like id || counter if i do something (some event) i want the counter's value(at a particular id) to increase by one , currently iam doing this : //get current value current_value = select counter from myTable where id='someValue' // increase value current_value++ //update table with current value update myTable set counter=current_value where id='someValue'; currently iam running 2 queries for this, please suggest me some way do it in one step.

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  • Mysql Limit column value repetition N times

    - by Paper-bat
    Hi at all, is my first question here, so be patient ^^ I'll go directly to problem, I have two table Customer (idCustomer, ecc.. ecc..) Comment (idCustomer, idComment, ecc.. ecc..) obviosly the two table are joined togheter, for example SELECT * FROM Comment AS co JOIN Customer AS cu ON cu.idCustomer = co.idCustomer With this I select all comment from that table associated with is Customer, but now I wanna limit the number of Comment by 2 max Comment per Customer. The first thing I see is to use 'GROUP BY cu.idCustomer' but it limit only 1 Comment per Customer, but I wanna 2 Comment per Customer.. how now to proceed?

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  • Adding new column in Sales Order View Items in Magento Admin

    - by fdierre
    In the admin interface of Magento I need to modify the tables in the Sales / Order / View order so that it shows, besides the products name, their manufacturer as well. I'm trying to look for the file to modify to make that happen. I thought I would find a section with all the columns that are displayed in app/code/core/Mage/Sales/Block/Order/Item/Renderer/Default.php but by inspecting it there seem to be no reference to the columns/product attributes. I also tried to modify app/design/adminhtml/default/default/template/sales/order/view/items/renderer/default.phtml by changing <?php echo $this->getColumnHtml($_item, 'name') ?> into <?php echo $this->getColumnHtml($_item, 'manufacturer') ?> but it changed nothing, so I suppose that file is not involved... Can anybody please point me to the right file to modify? Thank you!

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  • How to remove "Standard Error" column from xtable() output of an lm on R/RSweave/LaTeX

    - by Lucas Spangher
    I'm currently doing some data analysis on population data, so reporting the standard errors in the tables of parameter coefficients just doesn't really make statistical sense. I've done a fair bit of searching and can't find any way to customize the xtable output to remove it. Can anyone point me in the right direction? Thanks a lot, I didn't post this lightly; if it's something obvious, I apologize for having wasted time!

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  • A better way of getting a data table with various column types into string array

    - by Vlad
    This should be an easy one, looks like I got myself too confused. I get a table from a database, data ranges from varchar to int to Null values. Cheap and dirty way of converting this into a tab-delimited file that I already have is this (shrunken to preserve space, ugliness is kept on par with original): da.Fill(dt) ' da - DataAdapter ' ' dt - DataTable ' Dim lColumns As Long = dt.Columns.Count Dim arrColumns(dt.Columns.Count) As String Dim arrData(dt.Columns.Count) As Object Dim j As Long = 0 Dim arrData(dt.Columns.Count) As Object For i = 0 To dt.Rows.Count - 1 arrData = dt.Rows(i).ItemArray() For j = 0 To arrData.GetUpperBound(0) - 1 arrColumns(j) = arrData(j).ToString Next wrtOutput.WriteLine(String.Join(strFieldDelimiter, arrColumns)) Array.Clear(arrColumns, 0, arrColumns.GetLength(0)) Array.Clear(arrData, 0, arrData.GetLength(0)) Next Not only this is ugly and inefficient, it is also getting on my nerves. Besides, I want, if possible, to avoid the infamous double-loop through the table. I would really appreciate a clean and safe way of rewriting this piece. I like the approach that is used here - especially that is trying to solve the same problem that I have, but it crashes on me when I apply it to my case directly.

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  • SUM of column with Left Outer Join

    - by Matt
    I am trying to get the Count of all records that have at least on person who is authorized on the record. Basically, a Record can have more than one person associated with it. I want to return the count of Total Records, a count of total Authorized Records where at least 1 person is authorized, and a count of total NotAuthorized records where no person associated with record is authorized. It doesn't matter if one person is authorized per Record or if 3 people are authorized for that record, that should add 1 to the Authorized counter. The current query is incrementing Auth and Non auth for each person added per record rather, than one per record. If no people are assigned to the record that should also count towards Not Auth. SELECT Count(DISTINCT Record.RecordID) AS TotalRecords, SUM(CASE WHEN People.PersonLevel = 1 THEN 1 ELSE 0 END) AS Authorized, SUM(CASE WHEN People.PersonLevel <> 1 THEN 1 ELSE 0 END) AS NotAuthorized FROM Record LEFT OUTER JOIN RecordPeople ON Record.RecordID = RecordPeople.RecordID LEFT OUTER JOIN People ON RecordPeople.PersonID = People.PersonID

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  • Unable to bind in asp.net grid Template Column

    - by OneSmartGuy
    I am having trouble accessing the data field. I receive the error: Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control. I can get the value but using <%# getOpenJobs((string)Eval("ParentPart")) % but I need to use it in the if to display a certian picture if it passes the condition. Is there a better way to do this or am i just missing something simple? <telerik:GridTemplateColumn UniqueName="hasOpenJobs" HeaderText=""> <ItemTemplate> <% if (getOpenJobs((string)Eval("ParentPart")) > 1) { %> <img src="../images/job-icon.gif" alt="Open Jobs" /> <%} %> </ItemTemplate> </telerik:GridTemplateColumn>

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  • How to access Excel Max Column value?

    - by Phsika
    i try to create table from excel rows. however; excel columns : column1 has max 200 character row column2 has max 300 character row column3 has max 500 character row So i need to create sql create MyTable column3 nvarchar(500) according to Excel Max Character.

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  • How to convert a one column integer data file into a mask for image

    - by gavishna
    I have a data file which contains integers say in range 0-255 containing about 1000 integers which are random in nature.I want to use that as a mask or to multiply an image which is in RGb and another image which is in gray format. HOw do i go about this, how do i convert/represent this data file in matrix format of image dimension ?Kindly suggest. also is it possible to obtain a 3D histogram?

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