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  • Find the period of over speed ?

    - by Vimvq1987
    Just something interesting come in my mind. Assume that we have a table (in SQL Server) like this: Location Velocity Time What is the best way to determine over speed periods (speed barrier is defined) ? My first idea was loading the table into an array, and then iterate over array to find these periods: (Pseudo C# code) bool isOverSpeed = false; for (int i =0;i<arr.Length;i++) { if (!isOverSpeed) if (arr[i].Velocity > speedBarrier) { #insert the first record into another array. isOverSpeed = true; } if(isOverSpeed) if (arr[i].Velocity < speedBarrier) { #insert the record into that array isOverSpeed = false; } } It works, but somewhat "not very effectively". Is there a "smarter" way, such as a T-SQL query or another algorithm to do this?

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  • Optimal search queries

    - by Macros
    Following on from my last question http://stackoverflow.com/questions/2788082/sql-server-query-performance, and discovering that my method of allowing optional parameters in a search query is sub optimal, does anyone have guidelines on how to approach this? For example, say I have an application table, a customer table and a contact details table, and I want to create an SP which allows searching on some, none or all of surname, homephone, mobile and app ID, I may use something like the following: select * from application a inner join customer c on a.customerid = a.id left join contact hp on (c.id = hp.customerid and hp.contacttype = 'homephone') left join contact mob on (c.id = mob.customerid and mob.contacttype = 'mobile') where (a.ID = @ID or @ID is null) and (c.Surname = @Surname or @Surname is null) and (HP.phonenumber = @Homphone or @Homephone is null) and (MOB.phonenumber = @Mobile or @Mobile is null) The schema used above isn't real, and I wouldn't be using select * in a real world scenario, it is the construction of the where clause I am interested in. Is there a better approach, either dynamic sql or an alternative which can achieve the same result, without the need for many nested conditionals. Some SPs may have 10 - 15 criteria used in this way

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  • Oracle date / order by question

    - by user561793
    I want to select a date from oracle table formatted like select (to_char(req_date,'MM/YYYY')) but I also want to order the result set on this date format. I want them to be ordered like dates not strings. Like this 09/2009 10/2009 11/2009 12/2009 01/2010 02/2010 03/2010 04/2010 05/2010 06/2010 07/2010 08/2010 09/2010 10/2010 11/2010 12/2010 Not like 01/2010 02/2010 03/2010 04/2010 05/2010 06/2010 07/2010 08/2010 09/2009 09/2010 10/2009 10/2010 11/2009 11/2010 12/2009 12/2010 Any way to do this in sql? full sql is select (to_char(req_date,'MM/YYYY')) as monthYear,count(req_id) as count from REQUISITION_CURRENT t group by to_char(req_date,'MM/YYYY') Thanks

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  • What do C# Table Adapters actually return?

    - by Raven Dreamer
    I'm working on an application that manipulates SQL tables in a windows form application. Up until now, I've only been using the pre-generated Fill queries, and self-made update and delete queries (which return nothing). I am interested in storing the value of a single value from a single column (an 'nchar(15)' name), and though I have easily written the SQL code to return that value to the application, I have no idea what it will be returned as. SELECT [Contact First Name] FROM ContactSkillSet WHERE [Contact ID] = @CurrentID Can the result be stored directly as a string? Do I need to cast it? Invoke a toString method?

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  • MVC more specified models should be populated by more precise query too?

    - by KevinUK
    If you have a Car model with 20 or so properties (and several table joins) for a carDetail page then your LINQ to SQL query will be quite large. If you have a carListing page which uses under 5 properties (all from 1 table) then you use a CarSummary model. Should the CarSummary model be populated using the same query as the Car model? Or should you use a separate LINQ to SQL query which would be more precise? I am just thinking of performance but LINQ uses lazy loading anyway so I am wondering if this is an issue or not.

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  • Create tables for a dictionary?

    - by heffaklump
    I'm making a dictionary database in SQLite and need some tips. My SQL is a bit rusty ;) Would you consider this good SQL? It's done with Java JDBC. This is for creating the tables. CREATE TABLE word ( id INTEGER, entry STRING, pos STRING ); CREATE TABLE translation ( word_id INTEGER REFERENCES word(id), entry STRING ); And when filling with data i give each word a number (id) and that words translations get the same number as word_id. What would be the best way of pulling out translations for a specific word?

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  • Finding Most Recent Order for a Particular Item

    - by visitor
    I'm trying to write a SQL Query for DB2 Version 8 which retrieves the most recent order of a specific part for a list of users. The query receives a parameter which contains a list of customerId numbers and the partId number. For example, Order Table OrderID PartID CustomerID OrderTime I initially wanted to try: Select * from Order where OrderId = ( Select orderId from Order where partId = #requestedPartId# and customerId = #customerId# Order by orderTime desc fetch first 1 rows only ); The problem with the above query is that it only works for a single user and my query needs to include multiple users. Does anyone have a suggestion about how I could expand the above query to work for multiple users? If I remove my "fetch first 1 rows only," then it will return all rows instead of the most recent. I also tried using Max(OrderTime), but I couldn't find a way to return the OrderId from the sub-select. Thanks! Note: DB2 Version 8 does not support the SQL "TOP" function.

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  • How to predict result set row count?

    - by Saurabh Kumar
    I have an application where I create a big SQL query dynamically for SQL server 2008. This query is based on various search criteria which the user might give such as search by lastname, firstname, ssn etc. The requirement is that if the user gives a condition due to which the formed query might return a lot of rows(configurable for max N rows), then the application must send back a message instead to the user saying that he needs to refine his search query as the existing query will return too many rows. I would not want to bring back say, 5000 rows to the client and then discard that data just to show the user an error. What is an efficient way to tackle this issue?

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  • issue with selecting 1 or 0 in mysql db

    - by jason
    I am having trouble with the following SQL statement i have had this issue before but I cant remember how i fixed the problem, I am guessing the issue with this is that mysql sees 0 as null ? Note I didnt show the first part of the Select statement as its irrelevant my sql works, its showing rows with toffline that are = to 1 as well as 0... FROM table1 AS tb1 LEFT JOIN table2 AS tb2 ON tb2.id = tb1.id2 LEFT JOIN table3 AS tb3 ON tb3.id = tb1.id3 AND tb1.toffline = 0 I have also tried AND NOT tb1.toffline = 1 also WHERE tb1.toffline = 0 all with the same result...

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  • Using a database with C#

    - by Mike
    I have been trying to do something that I think would be really easy but have never used C# before and am having trouble with the details. I simple want to use a sql database with Visual C# Express 2008. For testing purposes I have a datagrid on my form that can reflect changes to the db. If i use this: codesTableAdapter.Fill(dataSet1.codes); The datagrid(dataset) will fill with the info from the sql database. If i then do something like this: codesTableAdapter.InsertQuery(txtCode.Text,txtName.Text); codesTableAdapter.Fill(dataSet1.codes); codesTableAdapter.Update(dataSet1); dataSet1.AcceptChanges(); The datagrid reflects the changes but if close the program and go to the database the changes are not there. When I open the program again the changes are not there. I have a feeling this isn't too clear as my understanding here is very low so please let me know what other info is needed. Thanks

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  • Check If Stored Procedure Returns Value

    - by Eric
    Hello all, I am using Linq 2 Sql in VS 2010, and I have the following stored procedure to check a username and password ALTER PROCEDURE dbo.CheckUser ( @username varchar(50), @password varchar(50) ) AS SELECT * FROM Users Where UserName=@username AND Password=@password The problem I'm having is that it throws an exception if the username and password are incorrect. I'd like to perform a check to see if there is a return value, rather than using try/catch to determine whether the procedure returned a value. Should I do this check in code (C#)? Or is there a way to do it in SQL? Thanks.

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  • Multiple &(AND) fails in query

    - by N e w B e e
    here is my query $sql = 'SELECT * FROM Orders INNER JOIN [Order Details] ON Orders.OrderNumber = [Order Details].OrderNumber WHERE Orders.CartID =2 AND [Order Details].Option10 Is Null AND [Order Details].Status="Shipped"'; this queries when entered in MS_Access sql view, returns the correct results, but when I copy and paste the same query in my php script, it fails and gives the error Too few parameters, expected 1... although data is there, query is working in access... Please note if I omitted on AND condition, it works eg if I removed shipped conidtion or is null condition, it works then too.. any hint? whats wrong with it?? any help?thanks

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  • Answers to “What source control system do you use?” (and some winners)

    - by jamiet
    About a month ago I posed a question here on my blog SQL Server devs–what source control system do you use, if any? (answer and maybe win free stuff) in which I asked SQL Server developers to answer the following questions: Are you putting your SQL Server code into a source control system? If so, what source control server software (e.g. TFS, Git, SVN, Mercurial, SourceSafe, Perforce) are you using? What source control client software are you using (e.g. TFS Team Explorer, Tortoise, Red Gate SQL Source Control, Red Gate SQL Connect, Git Bash, etc…)? Why did you make those particular software choices? Any interesting anecdotes to share in regard to your use of source control and SQL Server? I had some really great responses (I highly recommend going and reading them). I promised that the five best, most thought-provoking, responses (as determined by me) would win one of five pairs of licenses for Red Gate SQL Source Control and Red Gate SQL Connect; here are the five that I chose (note that if you responded but did not leave a means of getting in touch then you weren’t considered for one of the prizes – sorry): In general, I don't think the management overhead and licensing cost associated with TFS is worthwhile if all you're doing is using source control. To get value from TFS, at a minimum you need to be using team build, and possibly other stuff as well, such as the sharepoint integration. If that's all you need, then svn with Tortoise would be my first choice. If you want to add build automation later, you can do this with cruisecontrol (is it still called that?), JetBrains, etc. For a long time I thought that Redgate's claims about "bridging the SSMS-VS divide" were a load of hot air, since in my experience anyone who knew what they were doing was using Visual Studio, in particular SSDT and its predecessors. However, on a recent client I was putting in source control for the first time, and I discovered that the "divide" really does exist. That client has ended up using svn with Redgate SQL Source Control, with no build automation, but with scope to add it in the future. Gavin Campbell I think putting the DB under source control is a great idea.  I have issues with the earlier versions of SQL Source Control in that it provides little help in versioning the DB. I think the latest version merges SQL Compare and SQL Source Control together.  Which is how it should have been all along. Sure I have the DB scripts in SVN, but I can't automate DB builds and changes without more tools.  Frankly I'm surprised databases don't have some sort of versioning built into them. Nick Portelli Source control has been immensely useful and saved me from a lot of rework on more than one occasion.  I have learned that you have to be extremely careful checking in data.  Our system is internal only so during the system production run once a week, if there is a problem that I can fix easily(for example, a control table points to a file in the wrong environment), I'll do it directly in production so the run can continue as soon as possible since we have a specified time window.  We do full test runs to minimize this but it has come up once or twice.  We use Red-Gate source control to "push" from the test environment to the production environment.  There have been a couple of occasions where the test environment with the wrong setting was pushed back over the production environment because the change was made only in production.  Gotta keep an eye on that. Alan Dykes Goodness is it manual.  And can be extremely painful at times.  Not only are we running thin, we are constrained on the tools we can get ($$ must mean free).  Certainly no excuse, and a great opportunity to improve my skills by learning new things.  But...  Getting buy in a on a proven process or methodology is hard, takes time, and diverts us from development.  If SQL Source Control is easy to use and proven oh boy could you get some serious fans around here!  Seriously though, as the "accidental dba" of this shop any new ideas / easy to implement tools can make a world of difference in productivity and most importantly accuracy.  Manual = bad. :) John Hennesey (who left his email address) The one thing I would love to know more about is the unique challenges of working with databases as source code - you can store scripts, but are they written as deployment scripts with all the logic about how to apply them to an existing DB? Where is that baseline DB? Where's the data? How does a team share the data and the code? It's a real challenge. Merrill Aldrich Congratulations to the five of you. Red Gate will be in touch with you soon about your free licenses. Thank you to all those that responded. And again, go and check out all the responses – those above are only small proportion from what is a very interesting comment thread. @Jamiet

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  • NHibernate - does it work well with database-level cascading deletions on foreign key constraints

    - by Nelson LaQuet
    Dose nHibernate play well with database level cascading deletions? What I mean is that if I have a constraint set at the RDBMS level to cascade delete all orphans, will nHibernate invoke any custom delete logic at the application level if I were to delete an entity though nHibernate? Or should I remove the cascading deletions from the RDBMS level and just use the cascading delete feature of nHibernate itself by defining that behavior though its configuration? Thanks

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  • Proper way to use Linq with WPF

    - by Ingó Vals
    I'm looking for a good guide into the right method of using Linq to Sql together with WPF. Most guides only go into the bare basics like how to show data from a database but noone I found goes into how to save back to the database. Can you answer or point out to me a guide that can answer these questions. I have a separate Data project because the same data will also be used in a web page so I have the repository method. That means I have a seperate class that uses the DataContext and there are methods like GetAllCompanies() and GetCompanyById ( int id ). 1) Where there are collections is it best to return as a IQueryable or should I return a list? Inside the WPF project I have seen reccomendations to wrap the collection in a ObservabgleCollection. 2) Why should I use ObservableCollection and should I use it even with Linq / IQueryable Some properties of the linq entities should be editable in the app so I set them to two-way mode. That would change the object in the observableCollection. 3) Is the object in the ObservableCollection still a instance of the original linq entity and so is the change reflected in the database ( when submitchanges is called ) I should have somekind of save method in the repository. But when should I call it? What happens if someone edits a field but decides not to save it, goes to another object and edits it and then press save. Doesn't the original change also save? When does it not remember the changes to a linq entity object anymore. Should I instance the Datacontext class in each method so it loses scope when done. 4) When and how to call the SubmitChanges method 5) Should I have the DataContext as a member variable of the repository class or a method variable To add a new row I should create a new object in a event ( "new" button push ) and then add it to the database using a repo method. 6) When I add the object to the database there will be no new object in the ObservableCollection. Do I refresh somehow. 7) I wan't to reuse the edit window when creating new but not sure how to dynamically changing from referencing selected item from a listview to this new object. Any examples you can point out.

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  • How to make a Generic Repository?

    - by chobo2
    Hi I am wondering if anyone has any good tutorials(or maybe even a library that is already made and well documented) on making a generic repository. I am using currently linq to sql but it might change so I don't know if you can make a generic repository that would take little to no changes if I would say switch to entity framework. Thanks

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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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  • What does DataContext.GetTable<TEntry> do?

    - by Bryan
    Consider I have a DataContext db, and there is an Entity class User. So when System.Data.Linq.Table<User> table = db.GetTable<User>(); is called for the first time, does it pull the data from the database immediately, does it use deferred execution, or were the data already loaded from database when db was initialized?

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  • How to map LINQ EntitySet to List property in property setter?

    - by jlp
    In my model I have these entities: public interface IOrder { string Name {get;set;} List<IProduct> OrderedProducts {get;set;} } public interface IProduct {} In partial class generated by linq-to-sql I map these properties on my entity properties: public partial class Order : IOrder { List<IProduct> OrderedProducts { get { return this.L2SQLProducts.Cast<IProduct>.ToList(); } set { this.L2SQLProducts = ??? } } } How should setter look like?

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  • Transforming OLTP Relational Database to Data Warehousing Model

    - by Russ Cam
    What are the common design approaches taken in loading data from a typical Entity-Relationship OLTP database model into a Kimball star schema Data Warehouse/Marts model? Do you use a staging area to perform the transformation and then load into the warehouse? How do you link data between the warehouse and the OLTP database? Where/How do you manage the transformation process - in the database as sprocs, dts/ssis packages, or SQL from application code?

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  • How efficient is a details table?

    - by Jeffrey Lott
    At my job, we have pseudo-standard of creating one table to hold the "standard" information for an entity, and a second table, named like 'TableNameDetails', which holds optional data elements. On average, for every row in the main table will have about 8-10 detail rows in it. My question is: What kind of performance impacts does this have over adding these details as additional nullable columns on the main table?

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