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  • Advanced queries in HBase

    - by Teflon Ted
    Given the following HBase schema scenario (from the official FAQ)... How would you design an Hbase table for many-to-many association between two entities, for example Student and Course? I would define two tables: Student: student id student data (name, address, ...) courses (use course ids as column qualifiers here) Course: course id course data (name, syllabus, ...) students (use student ids as column qualifiers here) This schema gives you fast access to the queries, show all classes for a student (student table, courses family), or all students for a class (courses table, students family). How would you satisfy the request: "Give me all the students that share at least two courses in common"? Can you build a "query" in HBase that will return that set, or do you have to retrieve all the pertinent data and crunch it yourself in code?

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  • sqlite3 date operations when joining two tables in a view?

    - by duncan
    In short, how to add minutes to a datetime from an integer located in another table, in one select statement, by joining them? I have a table P(int id, ..., int minutes) and a table S(int id, int p_id, datetime start) I want to generate a view that gives me PS(S.id, P.id, S.start + P.minutes) by joining S.p_id=P.id The problem is, if I was generating the query from the application, I can do stuff like: select datetime('2010-04-21 14:00', '+20 minutes'); 2010-04-21 14:20:00 By creating the string '+20 minutes' in the application and then passing it to sqlite. However I can't find a way to create this string in the select itself: select p.*,datetime(s.start_at, formatstring('+%s minutes', p.minutes)) from p,s where s.p_id=p.id; Because sqlite as far the documentation tells, does not provide any string format function, nor can I see any alternative way of expressing the date modifiers.

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  • Interesting Row_Number() bug

    - by Joel Coehoorn
    I was playing with the Stack Exchange Data Explorer and ran this query: http://odata.stackexchange.com/stackoverflow/q/2828/rising-stars-top-50-users-ordered-on-rep-per-day Notice down in the results, rows 11 and 12 have the same value and so are mis-numbered, even though the row_number() function takes the same order by parameter as the query. I know the correct fix here is to specify an additional tie-breaker column in the order by clauses, but I'm more curious as to why/how the row_number() function returned different results on the same data? If it makes a difference anywhere, this runs on Azure.

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  • alter mysqldump file before import

    - by julio
    Hi-- I have a mysqldump file created from an earlier version of a product that can't be imported into a new version of the product, since the db structure has changed slightly (mainly altering a column that was NOT NULL DEFAULT 0 to UNIQUE KEY DEFAULT NULL). If I just import the old dump file, it will error out since the column that has default values of 0 now breaks the UNIQUE constraint. It would be easy enough to either manually alter the mysqldump file, or import into a temp table and change it, then copy to the new table. However, is there a way to do this programatically, so it will be repeatable and not manual? (this will need to happen for many instances of this product). I'm thinking something like disabling key constraints for the import, then setting all values that = 0 to NULL, then re-enabling the key constraints? Is this possible? Any help appreciated.

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  • MySQL: Efficient Blobbing?

    - by feklee
    I'm dealing with blobs of up to - I estimate - about 100 kilo bytes in size. The data is compressed already. Storage engine: InnoDB on MySQL 5.1 Frontend: PHP (Symfony with Propel ORM) Some questions: I've read somewhere that it's not good to update blobs, because it leads to reallocation, fragmentation, and thus bad performance. Is that true? Any reference on this? Initially the blobs get constructed by appending data chunks. Each chunk is up to 16 kilo bytes in size. Is it more efficient to use a separate chunk table instead, for example with fields as below? parent_id, position, chunk Then, to get the entire blob, one would do something like: SELECT GROUP_CONCAT(chunk ORDER BY position) FROM chunks WHERE parent_id = 187 The result would be used in a PHP script. Is there any difference between the types of blobs, aside from the size needed for meta data, which should be negligible.

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  • SQL query for an access database needed

    - by masfenix
    Hey guys, first off all sorry, i can't login using my yahoo provider. anyways I have this problem. Let me explain it to you, and then I'll show you a picture. I have a access db table. It has 'report id', 'recpient id', and 'recipient name' and 'report req'. What the table "means" is that do the user using that report still require it or can we decommission it. Here is how the data looks like (blocked out company userids and usernames): *check the link below, I cant post pictures cuz yahoo open id provider isnt working. So basically I need to have 3 select queries: 1) Select all the reports where for each report, ALL the users have said no to 'reportreq'. In plain English, i want a listing of all the reports that we have to decommission because no user wants it. 2) Select all the reports where the report is required, and the batchprintcopy is more then 0. This way we can see which report needs to be printed and save paper instead of printing all the reports. 3)A listing of all the reports where the reportreq field is empty. I think i can figure this one out myself. This is using Access/VBA and the data will be exported to an excel spreadsheet. I just a simple query if it exists, OR an alogorithm to do it quickly. I just tried making a "matrix" and it took about 2 hours to populate. https://docs.google.com/uc?id=0B2EMqbpeBpQkMTIyMzA5ZjMtMGQ3Zi00NzRmLWEyMDAtODcxYWM0ZTFmMDFk&hl=en_US

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  • Can in-memory SQLite databases scale with concurrency?

    - by Kent Boogaart
    In order to prevent a SQLite in-memory database from being cleaned up, one must use the same connection to access the database. However, using the same connection causes SQLite to synchronize access to the database. Thus, if I have many threads performing reads against an in-memory database, it is slower on a multi-core machine than the exact same code running against a file-backed database. Is there any way to get the best of both worlds? That is, an in-memory database that permits multiple, concurrent calls to the database?

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  • how to pass variables this in dynamic query

    - by Ranjana
    i using the dynamic query to pass the variables select a.TableName, COUNT(a.columnvalue) as '+'count'+' from Settings.ColumnMapping a where a.ColumnValue in ('+ @columnvalue +') and a.Value in (' + @value +') the @columnvalues = 'a','b','c' @value ='comm(,)','con(:)' how to pass this in dynamic query any idea???

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  • Extracting contents of ConnectionStrings in web.config in Silverlight Business application.

    - by webKite
    I am trying to read dataSource ad Catalog from connectionString in web.config in Silverlight business project. Unfortunately when I used "SqlConnectionStringBuilder", I could not read connectionstring the has "connectionString="metadata=res:///MainDatabase.Main.csdl|res:///MainDatabase.Main.ssdl|......."" where as it work for "connectionString="Data Source=My-PC\SQL_2008;Initial Catalog =...."". I could get them using "Split" however, I don't like that solution. Is there any way to get my requirements? Thanks

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  • Converting delimited string to multiple values in mysql

    - by epo
    I have a mysql legacy table which contains an client identifier and a list of items, the latter as a comma-delimited string. E.g. "xyz001", "foo,bar,baz". This is legacy stuff and the user insists on being able to edit a comma delimited string. They now have a requirement for a report table with the above broken into separate rows, e.g. "xyz001", "foo" "xyz001", "bar" "xyz001", "baz" Breaking the string into substrings is easily doable and I have written a procedure to do this by creating a separate table, but that requires triggers to deal with deletes, updates and inserts. This query is required rarely (say once a month) but has to be absolutely up to date when it is run, so e.g. the overhead of triggers is not warranted and scheduled tasks to create the table might not be timely enough. Is there any way to write a function to return a table or a set so that I can join the identifier with the individual items on demand?

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  • Creating a Doctrine query with a different number of ids

    - by frapet
    Is it possible to create a Doctrine query with a differnt number of ids coming from a submitted form? And if yes how? What I am trying to do is this: .... if ($input->isValid()) { $q = Doctrine_Query::create() ->from('Imm_Model_Images i') ->whereIn('i.ImageID = ?', array($input->ids)); $result = $q->fetchArray(); PS: ids come form the submitted form in an array as ids[]. Added Edit: chaged the above line: ->whereIn('i.ImageID = ?', array($input->ids)); with: ->whereIn('i.ImageID = array($input->ids)'); ...and it seems to work.

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  • Parse both symbols . and , as decimal digits delimiter in ASP.NET

    - by abatishchev
    I'm writing a banking system and my customer wants support both Russian and American numeric standards in decimal digits delimiter. Respectively . and ,. Now only , works properly. Perhaps because of web server's OS format (Russian is set). String like 2000.00 throws a FormatException: Input string was not in a correct format. How to fix that? Are there any other ideas except String.Replace('.', ',') on FormView.ItemInserting event?

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  • Java: JPQL search -similar- strings

    - by bguiz
    What methods are there to get JPQL to match similar strings? By similar I mean: Contains: search string is found within the string of the matches entity Case-insensitive Small mispellings: e.g. "arow" matches "arrow" I suspect the first two will be easy, however, I would appreciate help with the last one Thank you

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  • Conditional SELECT MySQL

    - by user188693
    Don't know if this is possible, but I'd like to select records based on the field value of recur_type, where the 'm' is the day of the week. If it's a weekly recurring event, I need to make sure this is a day it recurs on, otherwise, I want to return all days. however, I'm getting an empty result set: SELECT * FROM wp_fun_bec_events WHERE start_date <= '2009-10-12' AND ( end_date >= '2009-10-12' OR (recur_end > '0' AND recur_end >= '2009-10-12' ) ) AND ('m' IN ( CASE WHEN 'recur_type' = 'weekly' THEN recur_days ELSE 's/m/t/w/r/f/a' END ) ) ORDER BY start_date, start_time Any ideas??

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  • error in arabic script in mysql

    - by fusion
    i inserted data in mysql database which includes arabic script. while the output displays arabic correctly, the data in mysql looks like garbage. something like this: '&#1589;&#1614;&#1608;&#1605;&#1615; &#1579;&#1614;&#1604;&#1575;&#1579;&#1614;&#1577;&#1616; &#1571;&#1610;&#1617;&#1575;&#1605;&#1613; &#1605;&#1616;&#1606; &#1603;&#1615;&#1604;&#1617;&#1616; &#1588;&#1614;&#1607;&#1585;&#1613; &#1600; &#1571;&#1585;&#1576;&#1614;&#1593;&#1575;&#1569;&#1615; &#1576;&#1614;&#1610;&#1606;&#1614; &#1582;&#1614; should i be worried about this? if yes, how do i make it appear in proper arabic script in mysql? thanks.

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  • How do I select a fixed number of rows for each group?

    - by Maiasaura
    Here is some example data in a mysql table a b distance 15 44 250 94 31 250 30 41 250 6 1 250 95 18 250 72 84 500 14 23 500 55 24 500 95 8 500 59 25 500 40 73 500 65 85 500 32 50 500 31 39 500 22 25 500 37 11 750 98 39 750 15 57 750 9 22 750 14 44 750 69 22 750 62 50 750 89 35 750 67 65 750 74 37 750 52 36 750 66 53 750 82 74 1000 79 22 1000 98 41 1000 How do I query this table such that I get 2 rows per distance selected at random? A successful query will produce something like a b distance 30 41 250 95 18 250 59 25 500 65 85 500 15 57 750 89 35 750 79 22 1000 98 41 1000

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  • Database Design for One to One relationships

    - by Greelmo
    I'm trying to finalize my design of the data model for my project, and am having difficulty figuring out which way to go with it. I have a table of users, and an undetermined number of attributes that apply to that user. The attributes are in almost every case optional, so null values are allowed. Each of these attributes are one to one for the user. Should I put them on the same table, and keep adding columns when attributes are added (making the user table quite wide), or should I put each attribute on a separate table with a foreign key to the user table. I have decided against using the EAV model. Thanks!

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  • oracle search word in string

    - by Atul
    I want to search a word in string in ORACLE in which string is comma separated. Eg. String is ('MF1,MF2,MF3') and now I want to search whether 'MF' exists in that or not. If I am using instr('MF1,MF2,MF3','MF') it will give wrong result since I want to search Full MF in MF1 or MF2 or MF3.

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  • Selecting records with specific month and year in SQL Server 2005

    - by John
    I want to list records with a particular month and year. The table name is 'Arrival' and 'date' is the field that stores the date that the record was added. This is to be done from a C# application. For example, if the user selects month as 'April' and year as '2009' in the application, it will list all the records that were added on April,2009. (I only need the query, hope I can figure out the rest :) )

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  • Cannot add an entity that already exists.

    - by mazhar
    Code: public ActionResult Create(Group group) { if (ModelState.IsValid) { group.int_CreatedBy = 1; group.dtm_CreatedDate = DateTime.Now; var Groups = Request["Groups"]; int GroupId = 0; GroupFeature GroupFeature=new GroupFeature(); foreach (var GroupIdd in Groups) { // GroupId = int.Parse(GroupIdd.ToString()); } var Features = Request["Features"]; int FeatureId = 0; int t = 0; int ids=0; string[] Feature = Features.Split(',').ToArray(); //foreach (var FeatureIdd in Features) for(int i=0; i<Feature.Length; i++) { if (int.TryParse(Feature[i].ToString(), out ids)) { GroupFeature.int_GroupId = 35; GroupFeature.int_FeaturesId = ids; if (ids != 0) { GroupFeatureRepository.Add(GroupFeature); GroupFeatureRepository.Save(); } } } return RedirectToAction("Details", new { id = group.int_GroupId }); } return View(); } I am getting an error here Cannot add an entity that already exists. at this line GroupFeatureRepository.Add(GroupFeature); GroupFeatureRepository.Save();

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  • Converting time/date from XML file into MYSQL format

    - by IconicDigital
    One of the affiliate networks provides a feed with the following time/date format. <startDate>1349992800000</startDate> <endDate>1355266799999</endDate> My problem is I am trying to convert this to a MYSQL format, I have tried mktime and strtotime with no luck the date seems to come out wrong. I know this is the time since the Equinox, I am just not sure how to convert this to a MYSQL format.

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