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  • Opinions on sensor / reading / alert database design

    - by Mark
    I've asked a few questions lately regarding database design, probably too many ;-) However I beleive I'm slowly getting to the heart of the matter with my design and am slowly boiling it down. I'm still wrestling with a couple of decisions regarding how "alerts" are stored in the database. In this system, an alert is an entity that must be acknowledged, acted upon, etc. Initially I related readings to alerts like this (very cut down) : - [Location] LocationId [Sensor] SensorId LocationId UpperLimitValue LowerLimitValue [SensorReading] SensorReadingId Value Status Timestamp [SensorAlert] SensorAlertId [SensorAlertReading] SensorAlertId SensorReadingId The last table is associating readings with the alert, because it is the reading that dictate that the sensor is in alert or not. The problem with this design is that it allows readings from many sensors to be associated with a single alert - whereas each alert is for a single sensor only and should only have readings for that sensor associated with it (should I be bothered that the DB allows this though?). I thought to simplify things, why even bother with the SensorAlertReading table? Instead I could do this: [Location] LocationId [Sensor] SensorId LocationId [SensorReading] SensorReadingId SensorId Value Status Timestamp [SensorAlert] SensorAlertId SensorId Timestamp [SensorAlertEnd] SensorAlertId Timestamp Basically I'm not associating readings with the alert now - instead I just know that an alert was active between a start and end time for a particular sensor, and if I want to look up the readings for that alert I can do. Obviously the downside is I no longer have any constraint stopping me deleting readings that occurred during the alert, but I'm not sure that the constraint is neccessary. Now looking in from the outside as a developer / DBA, would that make you want to be sick or does it seem reasonable? Is there perhaps another way of doing this that I may be missing? Thanks. EDIT: Here's another idea - it works in a different way. It stores each sensor state change, going from normal to alert in a table, and then readings are simply associated with a particular state. This seems to solve all the problems - what d'ya think? (the only thing I'm not sure about is calling the table "SensorState", I can't help think there's a better name (maybe SensorReadingGroup?) : - [Location] LocationId [Sensor] SensorId LocationId [SensorState] SensorStateId SensorId Timestamp Status IsInAlert [SensorReading] SensorReadingId SensorStateId Value Timestamp There must be an elegant solution to this!

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  • Sorting Anonymous Types

    - by strobaek
    I have a question of how to sort an anonymous type. Using Linq2SQL I have the following query, which returns a list of submissions: var submissions = EventSubmissions .Where(s => s.EventId.Equals(eventId)); Consider the following interface (somewhat simplyfied): public interface IQuerySorter { IOrderedQueryable Sort(IQueryable query); IOrderedQueryable<T> Sort<T, U>(IQueryable<T> query, Expression<Func<T,U>> selector); ... } Using this interface allows me to implement a number of 'sorters', e.g. on Date, Rating or whether or not a submission has been nominated (for voting). sortedQuery = sorter.Sort(submissions) So far so good. A submission can be made "votable". I get the number of votes a nominated submission may have using the following query: var withVoteCount = submissions .Select(s => new {NumberOfVotes = s.Votes.Count(), Submission = s}); I would like to sort this new query by NumberOfVotes using my "general" sorter class, but run into the problem that the anonymous type/member does not seem to live outside the repository-method, hence I am unable to sort on it. Any input would be greatly appreciated.

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  • Use a stored procedure parameter for unit parameter of DATE_SUB

    - by Mike
    I would like to know if it's possible to pass a parameter to a mysql stored procedure and use this parameter as the unit parameter of the DATE_SUB function. It seems that the unit parameter is a reserved word so I don't know if there's a type for unit. Exemple of what I'm trying to do : DELIMITER $$ DROP PROCEDURE IF EXISTS `test` $$ CREATE DEFINER=`root`@`%` PROCEDURE `test`(param1 unit) BEGIN select DATE_SUB(now(), INTERVAL 1 param1); END $$ DELIMITER ;

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  • How can I write a clean Repository without exposing IQueryable to the rest of my application?

    - by Simucal
    So, I've read all the Q&A's here on SO regarding the subject of whether or not to expose IQueryable to the rest of your project or not (see here, and here), and I've ultimately decided that I don't want to expose IQueryable to anything but my Model. Because IQueryable is tied to certain persistence implementations I don't like the idea of locking myself into this. Similarly, I'm not sure how good I feel about classes further down the call chain modifying the actual query that aren't in the repository. So, does anyone have any suggestions for how to write a clean and concise Repository without doing this? One problem I see, is my Repository will blow up from a ton of methods for various things I need to filter my query off of. Having a bunch of: IEnumerable GetProductsSinceDate(DateTime date); IEnumberable GetProductsByName(string name); IEnumberable GetProductsByID(int ID); If I was allowing IQueryable to be passed around I could easily have a generic repository that looked like: public interface IRepository<T> where T : class { T GetById(int id); IQueryable<T> GetAll(); void InsertOnSubmit(T entity); void DeleteOnSubmit(T entity); void SubmitChanges(); } However, if you aren't using IQueryable then methods like GetAll() aren't really practical since lazy evaluation won't be taking place down the line. I don't want to return 10,000 records only to use 10 of them later. What is the answer here? In Conery's MVC Storefront he created another layer called the "Service" layer which received IQueryable results from the respository and was responsible for applying various filters. Is this what I should do, or something similar? Have my repository return IQueryable but restrict access to it by hiding it behind a bunch of filter classes like GetProductByName, which will return a concrete type like IList or IEnumerable?

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  • Ado JobStore use!

    - by aleo
    well i'm new in Quartz i'm following this tutorial and i configured my scheduler instance and quartz to use this properties: properties["quartz.jobStore.lockHandler.type"] = "Quartz.Impl.AdoJobStore.UpdateLockRowSemaphore, Quartz"; properties["quartz.jobStore.driverDelegateType"] = "Quartz.Impl.AdoJobStore.SqlServerDelegate, Quartz"; properties["quartz.jobStore.dataSource"] = "default"; properties["quartz.dataSource.default.connectionString"] = "Server=loclahost;Initial Catalog=aleo;Persist Security Info=True;User ID=userid;Password=password"; properties["quartz.dataSource.default.provider"] = "SqlServer-20"; properties["quartz.jobStore.type"] = "Quartz.Impl.AdoJobStore.JobStoreTX, Quartz"; properties["quartz.jobStore.useProperties"] = "true"; properties["quartz.jobStore.tablePrefix"] = "QRTZ_"; ISchedulerFactory schedFact = new Quartz.Impl.StdSchedulerFactory(properties); IScheduler sched = schedFact.GetScheduler(); sched.Start(); but what's next? i am new on C# but if someone explain to can understand :) and my question are how i will add jobs and triggers and stuff to the database? i also created the tables given in the Database/tables folder that comes with Quartz API thanks.

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  • Fill WinForms DataGridView From Anonymous Linq Query

    - by mdvaldosta
    // From my form BindingSource bs = new BindingSource(); private void fillStudentGrid() { bs.DataSource = Admin.GetStudents(); dgViewStudents.DataSource = bs; } // From the Admin class public static List<Student> GetStudents() { DojoDBDataContext conn = new DojoDBDataContext(); var query = (from s in conn.Students select new Student { ID = s.ID, FirstName = s.FirstName, LastName = s.LastName, Belt = s.Belt }).ToList(); return query; } I'm trying to fill a datagridview control in Winforms, and I only want a few of the values. The code compiles, but throws a runtime error: Explicit construction of entity type 'DojoManagement.Student' in query is not allowed. Is there a way to get it working in this manner?

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  • LEFT OUTER JOIN SUM doubles problem

    - by Michael
    Hi I've got two tables: Table: Shopping shop_id shop_name shop_time 1 Brian 40 2 Brian 31 3 Tom 20 4 Brian 30 Table:bananas banana_id banana_amount banana_person 1 1 Brian 2 1 Brian I now want it to print: Name: Tom | Time: 20 | Bananas: 0 Name: Brian | Time: 101 | Bananas: 2 I used this code: $result = dbquery("SELECT tz.*, tt.*, SUM(shop_time) as shoptime, count(banana_amount) as bananas FROM shopping tt LEFT OUTER JOIN bananas tz ON tt.shop_name=tz.banana_person GROUP by banana_person LIMIT 40 "); while ($data5 = dbarray($result)) { echo 'Name: '.$data5["shop_name"].' | Time: '.$data5["shoptime"].' | Bananas: '.$data5["bananas"].'<br>'; } The problem is that I get this instead: Name: Tom | Time: 20 | Bananas: 0 Name: Brian | Time: 202 | Bananas: 6 I just don't know how to get around this.

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  • ASP.NET MVC pagination problem????

    - by MD_Oppenheimer
    OK, This is starting to get mildly irritating. I tried to implement Twitter style paging using ASP.NET MVC and JQuery my problem is that when not using Request.IsAjaxRequest() (for users with javascript turned off) it works fine, obviously posting back the whole page. when I run the code for Request.IsAjaxRequest(), it skips entries, and does not return result in order. this is the code I have: public ActionResult Index(int? startRow) { StatusUpdatesRepository statusUpdatesRepository = new StatusUpdatesRepository(); if (!startRow.HasValue) startRow = Globals.Settings.StatusUpdatesSection.StatusUpdateCount;//5 Default starting row //Retrieve the first page with a page size of entryCount int totalItems; if (Request.IsAjaxRequest()) { IEnumerable<StatusUpdate> PagedEntries = statusUpdatesRepository.GetLastStatusUpdates(startRow.Value,Globals.Settings.StatusUpdatesSection.StatusUpdateCount, out totalItems); if (startRow < totalItems) AddMoreUrlToViewData(startRow.Value); return View("StatusUpdates", PagedEntries); } //Retrieve the first page with a page size of global setting // First run skip 0 take 5 IEnumerable<StatusUpdate> entries = statusUpdatesRepository.GetLastStatusUpdates(0,startRow.Value, out totalItems); if (startRow < totalItems) AddMoreUrlToViewData(startRow.Value); return View(entries); } private void AddMoreUrlToViewData(int entryCount) { ViewData["moreUrl"] = Url.Action("Index", "Home", new { startRow = entryCount + Globals.Settings.StatusUpdatesSection.StatusUpdateCount }); } My GetLastStatusUpdates function: public IQueryable GetLastStatusUpdates(int startRowIndex, int maximumRows,out int statusUpdatesCount ) { statusUpdatesCount = db.StatusUpdates.Count(); return db.StatusUpdates .Skip(startRowIndex) .Take(maximumRows) .OrderByDescending(s = s.AddedDate); } Really fresh out out of ideas as to why this is not working properly when responding to a Request.IsAjaxRequest(), ie when I turn of javascript in the browser, the code works perfectly, except I don't want to repost the whole page????

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  • Oracle custom sort

    - by Carter
    The query... select distinct name from myTable returns a bunch of values that start with the following character sequences... ADL* FG* FH* LAS* TWUP* Where '*' is the remainder of the string. I want to do an order by that sorts in the following manner... ADL* LAS* TWUP* FG* FH* But then I also want to sort within each name in the standard order by fashion. So, an example, if I have the following values LAS-21A TWUP-1 FG999 FH3 ADL99999 ADL88888 ADL77777 LAS2 I want it to be sorted like this... ADL77777 ADL88888 ADL99999 LAS2 TWUP-1 FG999 FH3 I initially thought I could accomplish this vias doing an order by decode(blah) with some like trickery inside of the decode but I've been unable to accomplish it. Any insights?

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  • DNN 5.2.3 Stored Procedures executing numerous times during page loads

    - by David Neale
    After tracing the DB activity from a DNN 5.2.3 site I noticed that there are numerous identical calls to the database whilst loading the home page for the first time (afterwards the caching works successfully). //Procedure : Number of executions exec dbo.aspnet_Membership_GetUserByName @ApplicationName=N'DotNetNuke',@UserName=N'MYDOMAIN\ME',@UpdateLastActivity=0,@CurrentTimeUtc='2010-03-24 10:04:15:223' : 22 exec dbo.GetPortalAliasByPortalID @PortalID=0 : 15 exec dbo.GetUserProfile @UserID=8 : 11 exec dbo.GetUser @PortalID=0,@UserID=8 : 10 exec dbo.GetDatabaseVersion : 2 exec dbo.GetUserCountByPortal @PortalId=0: 2 exec dbo.GetDesktopModules : 2 exec dbo.KB_XMod_Forms_List @PortalId=0 : 2 exec dbo.KB_XMod_Templates_List @PortalId=0,@TemplateType=-1 : 2 Why so many duplicates?

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  • using securestring for a sql connection

    - by Rick
    Hi, I want to use a SecureString to hold a connection string for a database. But as soon as I set the SqlConnection object's ConnectionString property to the value of the securestring surely it will become visible to any other application that is able to read my application's memory? I have made the following assumptions: a) I am not able to instantiate a SqlConnection object outside of managed memory b) any string within managed memory can be read by an application such as Hawkeye

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  • Gridview buttonfield works LinkButton doesn't

    - by Karsten
    I've been fighting this problem for many hours now and could really use some help :-) This is the grid <asp:GridView ID="annonceView" runat="server" AutoGenerateColumns="False" DataKeyNames="Id" DataSourceID="dataSourceAnnoncer"> <Columns> <asp:BoundField DataField="Productname" HeaderText="Productname" /> <asp:buttonfield buttontype="Link" commandname="Delete" text="Delete"/> <asp:TemplateField HeaderText="Administration"> <ItemTemplate> <asp:LinkButton ID="lnkBtnDelete" runat="server" Text="Delete" CausesValidation="False" CommandName="Delete" OnClientClick="return confirm('Delete?')" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> <asp:LinqDataSource ID="dataSourceAnnoncer" runat="server" ContextTypeName="Namespcae.TheContext" EnableDelete="True" TableName="Annoncer"> </asp:LinqDataSource> Clicking the buttonfield deletes the record just fine. Clicking the LinkButton doesn't work. I get a postback and the grid is shown as empty and no record is deleted. Seems like an empty databinding. I have tried to create a custom OnClick, OnCommand event for the LinkButton, but neither are fired. The OnRowCommand isn't fired either. I don't manually DataBind in the codebehind.

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  • SubSonic missing stored procedures in StoredProcedures.cs when generated with SubCommander sonic.exe

    - by Mark
    We have been using SubSonic to generate our DAL with a lot of success on VS2005 and SubSonic Tools 2.0.3. SubSonic Tools do not work on VS2008 (as far as we can work out) so we have tried to use SubCommander\sonic.exe and are now hitting some problems. When we regenerate the project using SubCommander\sonic.exe and try to compile we get some errors reporting missing members (which should have been automatically generated based on the stored procedures we have). On closer inspection it looks like my StoredProcedures.cs file is missing some (not all) automatically generated methods for my classes. As an example, I have 2 procs: [dbo]._ClassA_Func1 [dbo]._ClassA_Func2 Only one of these is being generated in the StoredProcedures.cs file. These methods generate fine using the SubSonic Tools plugin. We have tried now with versions 2.1 and 2.2 of SubSonic with the same issue. We are still on .NET 2.0 so cannot use SubSonic 3.0. I have checked the permissions of both procs using fn_my_permissions and they seem identical. Does anyone have any ideas on what I can check? Thanks -- Mark

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  • Why does GetSqlDecimal throw when GetDecimal doesn't?

    - by I. J. Kennedy
    I have a database table that has a column of type money, allowing nulls. Using a SqlDataReader named reader, I can do decimal d = reader.GetDecimal(1); which works, unless of course we're reading a null. If I try using SqlDecimal instead--and I thought the whole point of the SqlTypes was to deal with nulls--then I get an invalid cast, whether or not the value is null. SqlDecimal s = reader.GetSqlDecimal(1); // throws an invalid cast exception What am I doing wrong? Do I really have to write a conditional statement to shepherd the value from the database to a SqlDecimal variable?

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  • How to JOIN a COUNT from a table, and then effect that COUNT with another JOIN

    - by jakenoble
    Hi I have three tables Post ID Name 1 'Something' 2 'Something else' 3 'One more' Comment ID PostId ProfileID Comment 1 1 1 'Hi my name is' 2 2 2 'I like cakes' 3 3 3 'I hate cakes' Profile ID Approved 1 1 2 0 3 1 I want to count the comments for a post where the profile for the comment is approved I can select the data from Post and then join a count from Comment fine. But this count should be dependent on if the Profile is approved or not. The results I am expecting is CommentCount PostId Count 1 1 2 0 3 1 Thanks for any help.

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  • C# SqlDataReader = null?

    - by tom
    myConnection.Open(); SqlDataReader myreader; myreader = SqlCom.ExecuteReader(); int id = -1; ErrorBox.InnerHtml = "Username:" + sUserName + ":" + sPassword + ":<br/>"; while (myreader.HasRows) { id = (int)myreader["id"]; String sUser = (String)myreader["Username"]; String sPass = (String)myreader["Password"]; ErrorBox.InnerHtml += "UserId is <b>" + id + "</b> " + sUser + ":" + sPass + ":<br >"; Session["LoginID"] = id; Server.Transfer(ReturnPage); } if (id == -1) { ErrorBox.InnerHtml = "Incorrect Password"; } myConnection.Close(); I added a breakpoint at myreader = SqlCom.ExecuteReader(); and it keeps returning myreader as null and HasRows = False, but it does have rows. So, it keeps validating my login as incorrect since id = -1, Help?

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  • how to get mysql query as xml?

    - by mobibob
    I recall reading about XML support from MySql. Does anyone know how to get XML without writing code? My client-protocol expects XML and I have a data source that I can access from a web app (JSP using JDBC).

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  • Row Number for group by ?

    - by Damien Joe
    I have table structure like Category EmpName 1 Harry 1 John 1 Ford 2 James 2 Mark 2 Shane 3 Oliver 3 Ted I want results like Category EmpName RowNumber 1 Harry 1 1 John 2 1 Ford 3 2 James 1 2 Mark 2 2 Shane 3 3 Oliver 1 3 Ted 2 I am using db2 and row_number() is not working for different groups of records.

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  • Predicate problem in ToSelectList

    - by Stefanvds
    the ToSelectList method I have: public static IList<SelectListItem> ToSelectList<T>(this IEnumerable<T> itemsToMap, Func<T, string> textProperty, Func<T, string> valueProperty, Predicate<T> isSelected) { var result = new List<SelectListItem>(); foreach (var item in itemsToMap) { result.Add(new SelectListItem { Value = valueProperty(item), Text = textProperty(item), Selected = isSelected(item) }); } return result; } when I call this method here: public static List<SelectListItem> lesgeverList(int selectedID) { NASDataContext _db = new NASDataContext(); var lesg = (from l in _db.Lesgevers where l.LG_Naam != "leeg" orderby l.LG_Naam select l).ToSelectList(m => m.LG_Naam + " " + m.LG_Vnaam, m => m.LG_ID.ToString(), m => m.LG_ID == selectedID); return lesg.ToList(); } the selectlist I get has the selectedID as selected. now, when I want to have multiple selected items, I give a list of Lesgevers public static List<SelectListItem> lesgeverList(List<Lesgever> lg) { NASDataContext _db = new NASDataContext(); var test = (from l in _db.Lesgevers where l.LG_Naam != "leeg" && lg.Contains(l) orderby l.LG_Naam, l.LG_Vnaam select l).ToList(); var lesg = (from l in _db.Lesgevers where l.LG_Naam != "leeg" orderby l.LG_Naam, l.LG_Vnaam select l).ToSelectList(m => m.LG_Naam + " " + m.LG_Vnaam, m => m.LG_ID.ToString(), m => lg.Contains(m)); return lesg.ToList(); } the var test does return the Lesgevers that i have in the lg List, in my 'var lesg', there are no selectlistitem's selected at all. where is my mistake? :) how do I fix thix?

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  • Foreign key reference to a two-column primary key

    - by Adam Ernst
    One of my tables has a two-column primary key: CREATE TABLE tournament ( state CHAR(2) NOT NULL, year INT NOT NULL, etc..., PRIMARY KEY(state, year) ); I want a reference to the tournament table from another table, but I want this reference to be nullable. Here's how I might do it, imagining that a winner doesn't necessarily have a tournament: CREATE TABLE winner ( name VARCHAR NOT NULL, state CHAR(2) NULL, year INT NULL ); If state is null but year is not, or vice-versa, the table would be inconsistent. I believe the following FOREIGN KEY constraint fixes it: ALTER TABLE winner ADD CONSTRAINT FOREIGN KEY fk (name, state) REFERENCES tournament (name, state); Is this the proper way of enforcing consistency? Is this schema properly normalized?

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