sql constraint and keys - Page 284

django models : How to have variable number of foreign keys in a model ?

- by Rohit

For instance, Model Resume contains variable number of Model Project 's, What should be my models and relationships between them to achieve this ? Thanks in advance.

Why is django admin not accepting Nullable foreign keys?

Here is a simplified version of one of my models: class ImportRule(models.Model): feed = models.ForeignKey(Feed) name = models.CharField(max_length=255) feed_provider_category = models.ForeignKey(FeedProviderCategory, null=True) target_subcategories = models.ManyToManyField(Subcategory) This class manages a rule for importing a list of items from a feed into the database. The admin system won't let me add an ImportRule without selecting a feed_provider_category despite it being declared in the model as nullable. The database (SQLite at the moment) even checks out ok: >>> .schema ... CREATE TABLE "someapp_importrule" ( "id" integer NOT NULL PRIMARY KEY, "feed_id" integer NOT NULL REFERENCES "someapp_feed" ("id"), "name" varchar(255) NOT NULL, "feed_provider_category_id" integer REFERENCES "someapp_feedprovidercategory" ("id"), ); ... I can create the object in the python shell easily enough: f = Feed.objects.get(pk=1) i = ImportRule(name='test', feed=f) i.save() ...but the admin system won't let me edit it, of course. How can I get the admin to let me edit/create objects without specifying that foreign key?

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Generic Type constraint in .net

- by Jose

Okay I'm looking for some input, I'm pretty sure this is not currently supported in .NET 3.5 but here goes. I want to require a generic type passed into my class to have a constructor like this: new(IDictionary<string,object>) so the class would look like this public MyClass<T> where T : new(IDictionary<string,object>) { T CreateObject(IDictionary<string,object> values) { return new T(values); } } But the compiler doesn't support this, it doesn't really know what I'm asking. Some of you might ask, why do you want to do this? Well I'm working on a pet project of an ORM so I get values from the DB and then create the object and load the values. I thought it would be cleaner to allow the object just create itself with the values I give it. As far as I can tell I have two options: 1) Use reflection(which I'm trying to avoid) to grab the PropertyInfo[] array and then use that to load the values. 2) require T to support an interface like so: public interface ILoadValues { void LoadValues(IDictionary values); } and then do this public MyClass<T> where T:new(),ILoadValues { T CreateObject(IDictionary<string,object> values) { T obj = new T(); obj.LoadValues(values); return obj; } } The problem I have with the interface I guess is philosophical, I don't really want to expose a public method for people to load the values. Using the constructor the idea was that if I had an object like this namespace DataSource.Data { public class User { protected internal User(IDictionary<string,object> values) { //Initialize } } } As long as the MyClass<T> was in the same assembly the constructor would be available. I personally think that the Type constraint in my opinion should ask (Do I have access to this constructor? I do, great!) Anyways any input is welcome.

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Foreign key definition in sqlite

- by Hab

Cant add foreign key constraint in sqlite ...........

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Force.com presents Database.com SQL Azure/Amazon RDS unfazed

- by Sarang

At the DreamForce 2010 event in San Francisco Force.com unveiled their next big thing in the Fat SaaS portfolio "Database.com". I am still wondering how would they would've shelled out for that domain name. Now why would a already established SaaS player foray into a key building block like Database? Potentially allowing enterprises to build apps that do not utilize the Force.com stack! One key reason is being seen as the Fat SaaS player with evey trick in the SaaS space under his belt. You want CRM come hither, want a custom development PaaS like solution welcome home (VMForce), want all your apps to talk to a cloud DB and minimize latency by having it reside closer to you cloud apps? You've come to the right place sire! Other is potentially killing foray of smaller DB players like Oracle (Not surprisingly, the Database.com offering is a highly customized and scalable Oracle database) from entering the lucrative SaaS db marketplace. The feature set promised looks great out of the box for someone who likes to visualize cool new architectures. The ground realities are certainly going to be a lot different considering the SOAP/REST style access patterns in lieu of the comfortable old shoe of SQL. Microsoft suffered heavily with SDS (SQL Data Services) offering in early 2009 and had to pull the plug on the product only to reintroduce as a simple SQL Server in the cloud, SQL Windows Azure. Though MSFT is playing cool by providing OData semantics to work with SQL Windows Azure satisfying atleast some needs of the Web-Style to a DB. The other features like Social data models including Profiles, Status updates, feeds seem interesting as well. (Although I beleive social is just one of the aspects of large scale collaborative computing). All these features start "Free" for devs its a good news but the good news stops here. The overall pricing model of $ per Users per Transactions / Month is highly disproportionate compared to Amazon RDS (Based on MySQL) or SQL Windows Azure (Based on MSSQL). Roger Jennigs of Oakleaf did an interesting comparo based on 3, 10, 100, 500 users and it turns out that Database.com going by current understanding is way too expensive for the services on offer. The offering may not impact the decision for DotNet shops mulling their cloud stategy or even some Java/MySQL shops thinking about Amazon RDS, however for enterprises having already invested in other force.com offerings this could be a very important piece in the cloud strategy jigsaw. One which would address a key cloud DB issue of "Latency" for them at least it will help having the DB in the neighborhood. The tooling and "SQL like" access provider drivers (Think ODBC/JDBC) will be available later this year. Progress Software has already announced their JDBC driver stack for Database.com. It remains to be seen how effective the overall solutions proves to be in the longer run but for starts its a important decision towards consolidating Force.com's already strong positioning in the SaaS space. As always contrasting views are welcome! :)

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Parsing XML in a non-XML column

- by slugster

Hi, i am reasonably proficient with SQLServer, but i'm not a DBA so i'm not sure how to approach this. I have an XML chunk stored in an ntext column. Due to it being a legacy database and the requirements of the project i cannot change the table (yet). This is an example of the data i need to manipulate: <XmlSerializableHashtable xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Entries> <Entry> <key xsi:type="xsd:string">CurrentYear</key><value xsi:type="xsd:string">2010</value> </Entry> <Entry> <key xsi:type="xsd:string">CurrentMonth</key><value xsi:type="xsd:string">4</value> </Entry> </Entries> </XmlSerializableHashtable> each row will have a chunk like this, but obviously with different keys/values in the XML. Is there any clever way i can parse this XML in to a name/value pairs style view? Or should i be using SQLServer's XML querying abilities even though it isn't an XML column? If so, how would i query a specific value out of that column? (Note: adding a computed XML column on the end of the table is a possibility, if that helps). Thanks for any assistance!

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LINQ(2 SQL) Insert Multiple Tables Question

- by Refracted Paladin

I have 3 tables. A primary EmploymentPlan table with PK GUID EmploymentPlanID and 2 FK's GUID PrevocServicesID & GUID JobDevelopmentServicesID. There are of course other fields, almost exclusively varchar(). Then the 2 secondary tables with the corresponding PK to the primary's FK's. I am trying to write the LINQ INSERT Method and am struggling with the creation of the keys. Say I have a method like below. Is that correct? Will that even work? Should I have seperate methods for each? Also, when INSERTING I didn't think I needed to provide the PK for a table. It is auto-generated, no? Thanks, public static void InsertEmploymentPlan(int planID, Guid employmentQuestionnaireID, string user, bool communityJob, bool jobDevelopmentServices, bool prevocServices, bool transitionedPrevocIntegrated, bool empServiceMatchPref) { using (var context = MatrixDataContext.Create()) { var empPrevocID = Guid.NewGuid(); var prevocPlan = new tblEmploymentPrevocService { EmploymentPrevocID = empPrevocID }; context.tblEmploymentPrevocServices.InsertOnSubmit(prevocPlan); var empJobDevID = Guid.NewGuid(); var jobDevPlan = new tblEmploymentJobDevelopmetService() { JobDevelopmentServicesID = empJobDevID }; context.tblEmploymentJobDevelopmetServices.InsertOnSubmit(jobDevPlan); var empPlan = new tblEmploymentQuestionnaire { CommunityJob = communityJob, EmploymentQuestionnaireID = Guid.NewGuid(), InsertDate = DateTime.Now, InsertUser = user, JobDevelopmentServices = jobDevelopmentServices, JobDevelopmentServicesID =empJobDevID, PrevocServices = prevocServices, PrevocServicesID =empPrevocID, TransitionedPrevocToIntegrated =transitionedPrevocIntegrated, EmploymentServiceMatchPref = empServiceMatchPref }; context.tblEmploymentQuestionnaires.InsertOnSubmit(empPlan); context.SubmitChanges(); } } I understand I can use more then 1 InsertOnSubmit, See SO ? HERE, I just don't understand how that would apply to my situation and the PK/FK creation.

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LINQ-To-SQL and Mapping Table Deletions

- by Jake

I have a many-to-many relationship between two tables, let's say Friends and Foods. If a friend likes a food I stick a row into the FriendsFoods table, like this: ID Friend Food 1 'Tom' 'Pizza' FriendsFoods has a Primary Key 'ID', and two non-null foreign keys 'Friend' and 'Food' to the 'Friends' and 'Foods' tables, respectively. Now suppose I have a Friend tom .NET object corresponding to 'Tom', and Tom no longer likes pizza (what is wrong with him?) FriendsFoods ff = tblFriendsFoods.Where(x => x.Friend.Name == 'Tom' && x.Food.Name == 'Pizza').Single(); tom.FriendsFoods.Remove(ff); pizza.FriendsFoods.Remove(ff); If I try to SubmitChanges() on the DataContext, I get an exception because it attempts to insert a null into the Friend and Food columns in the FriendsFoods table. I'm sure I can put together some kind of convoluted logic to track changes to the FriendsFoods table, intercept SubmitChanges() calls, etc to try and get this to work the way I want, but is there a nice, clean way to remove a Many-To-Many relationship with LINQ-To-SQL?

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NHibernate Mapping and Querying Where Tables are Related But No Foreign Key Constraint

- by IanT8

I'm fairly new to NHibernate, and I need to ask a couple of questions relating to a very frequent scenario. The following simplified example illustrates the problem. I have two tables named Equipment and Users. Users is a set of system administrators. Equipment is a set of machinery. Tables: Users table has UserId int and LoginName nvarchar(64). Equipment table has EquipId int, EquipType nvarchar(64), UpdatedBy int. Behavior: System administrators can make changes to Equipment, and when they do, the UpdatedBy field of Equipment is "normally" set to their User Id. Users can be deleted at any time. New Equipment items have an UpdatedBy value of null. There's no foreign key constraint on Equipment.UpdatedBy which means: Equipment.UpdatedBy can be null. Equipment.UpdatedBy value can be = existing User.UserId value Equipment.UpdatedBy value can be = non-existent User.UserId value To find Equipment and who last updated the Equipment, I might query like this: select E.EquipId, E.EquipName, U.UserId, U.LoginName from Equipment E left outer join Users U on. E.UpdatedBy = U.UserId Simple enough. So how to do that in NHibernate? My mappings might be as follows: <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Data" assembly="Data"> <class name="User" table="Users"> <id name="Id" column="UserId" unsaved-value="0"> <generator class="native" /> </id> <property name="LoginName" unique="true" not-null="true" /> </class> <class name="Equipment" table="Equipment"> <id name="Id" column="EquipId" type="int" unsaved-value="0"> <generator class="native" /> </id> <property name="EquipType" /> <many-to-one name="UpdatedBy" class="User" column="UpdatedBy" /> </class> </hibernate-mapping> So how do I get all items of equipment and who updated them? using (ISession session = sessionManager.OpenSession()) { List<Data.Equipment> equipList = session .CreateCriteria<Data.Equipment>() // Do I need to SetFetchmode or specify that I // want to join onto User here? If so how? .List<Data.Equipment>(); foreach (Data.Equipment item in equipList) { Debug.WriteLine("\nEquip Id: " + item.Id); Debug.WriteLine("Equip Type: " + item.EquipType); if (item.UpdatedBy.Country != null) Debug.WriteLine("Updated By: " + item.UpdatedBy.LoginName); else Debug.WriteLine("Updated by: Nobody"); } } When Equipment.UpdatedBy = 3 and there is no Users.UserId = 3, the above fail I also have a feeling that the generated SQL is a select all from Equipment followed by many select columns from Users where UserId = n whereas I'd expected NHibernate to left join as per my plain ordinary SQL and do one hit. If I can tell NHibernate to do the query in one hit, how do I do that? Time is of the essence on my project, so any help you could provide is gratefully received. If you're speculating about how NHibernate might work in this scenario, please say you're not absolutely sure. Many thanks.

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SQL query mixing aggregated results and single values

- by Paul Flowerdew

I have a table with transactions. Each transaction has a transaction ID, and accounting period (AP), and a posting value (PV), as well as other fields. Some of the IDs are duplicated, usually because the transaction was done in error. To give an example, part of the table might look like: ID PV AP 123 100 2 123 -100 5 In this case the transaction was added in AP2 then removed in AP5. Another example would be: ID PV AP 456 100 2 456 -100 5 456 100 8 In the first example, the problem is that if I am analyzing what was spent in AP2, there is a transaction in there which actually shouldn't be taken into account because it was taken out again in AP5. In the second example, the second two transactions shouldn't be taken into account because they cancel each other out. I want to label as many transactions as possible which shouldn't be taken into account as erroneous. To identify these transactions, I want to find the ones with duplicate IDs whose PVs sum to zero (like ID 123 above) or transactions where the PV of the earliest one is equal to sum(PV), as in the second example. This second condition is what is causing me grief. So far I have SELECT * FROM table WHERE table.ID IN (SELECT table.ID FROM table GROUP BY table.ID HAVING COUNT(*) > 1 AND (SUM(table.PV) = 0 OR SUM(table.PV) = <PV of first transaction in each group>)) ORDER BY table.ID; The bit in chevrons is what I'm trying to do and I'm stuck. Can I do it like this or is there some other method I can use in SQL to do this? Edit 1: Btw I forgot to say that I'm using SQL Compact 3.5, in case it matters. Edit 2: I think the code snippet above is a bit misleading. I still want to mark out transactions with duplicate IDs where sum(PV) = 0, as in the first example. But where the PV of the earliest transaction = sum(PV), as in the second example, what I actually want is to keep the earliest transaction and mark out all the others with the same ID. Sorry if that caused confusion. Edit 3: I've been playing with Clodoaldo's solution and have made some progress, but still can't get quite what I want. I'm trying to get the transactions I know for certain to be erroneous. Suppose the following transactions are also in the table: ID PV AP 789 100 2 789 200 5 789 -100 8 In this example sum(PV) < 0 and the earliest PV < sum(PV) so I don't want to mark any of these out. If I modify Clodoaldo's query as follows: select t.* from t left join ( select id, min(ap) as ap, sum(pv) as sum_pv from t group by id having sum(pv) <> 0 ) s on t.id = s.id and t.ap = s.ap and t.pv = s.sum_pv where s.id is null This gives the result ID PV AP 123 100 2 123 -100 5 456 -100 5 456 100 8 789 100 3 789 200 5 789 -100 8 Whilst the first 4 transactions are ok (they would be marked out), the 789 transactions are also there, and I don't want them. But I can't figure out how to modify the query so that they're not included. Any ideas?

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Insert Error:CREATE DATABASE permission denied in database 'master'. cannot attach the file

- by user1300580

i have a register page on my website I am creating and it saves the data entered by the user into a database however when I click the register button i am coming across the following error: Insert Error:CREATE DATABASE permission denied in database 'master'. Cannot attach the file 'C:\Users\MyName\Documents\MyName\Docs\Project\SJ\App_Data\SJ-Database.mdf' as database 'SJ-Database'. These are my connection strings: <connectionStrings> <add name="ApplicationServices" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/> <add name="MyConsString" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|SJ-Database.mdf; Initial Catalog=SJ-Database; Integrated Security=SSPI;" providerName="System.Data.SqlClient" /> </connectionStrings> Register page code: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data; using System.Data.SqlClient; public partial class About : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } public string GetConnectionString() { //sets the connection string from your web config file "ConnString" is the name of your Connection String return System.Configuration.ConfigurationManager.ConnectionStrings["MyConsString"].ConnectionString; } private void ExecuteInsert(string name, string gender, string age, string address, string email) { SqlConnection conn = new SqlConnection(GetConnectionString()); string sql = "INSERT INTO Register (Name, Gender, Age, Address, Email) VALUES " + " (@Name,@Gender,@Age,@Address,@Email)"; try { conn.Open(); SqlCommand cmd = new SqlCommand(sql, conn); SqlParameter[] param = new SqlParameter[6]; //param[0] = new SqlParameter("@id", SqlDbType.Int, 20); param[0] = new SqlParameter("@Name", SqlDbType.VarChar, 50); param[1] = new SqlParameter("@Gender", SqlDbType.Char, 10); param[2] = new SqlParameter("@Age", SqlDbType.Int, 100); param[3] = new SqlParameter("@Address", SqlDbType.VarChar, 50); param[4] = new SqlParameter("@Email", SqlDbType.VarChar, 50); param[0].Value = name; param[1].Value = gender; param[2].Value = age; param[3].Value = address; param[4].Value = email; for (int i = 0; i < param.Length; i++) { cmd.Parameters.Add(param[i]); } cmd.CommandType = CommandType.Text; cmd.ExecuteNonQuery(); } catch (System.Data.SqlClient.SqlException ex) { string msg = "Insert Error:"; msg += ex.Message; throw new Exception(msg); } finally { conn.Close(); } } protected void cmdRegister_Click(object sender, EventArgs e) { if (txtRegEmail.Text == txtRegEmailCon.Text) { //call the method to execute insert to the database ExecuteInsert(txtRegName.Text, txtRegAge.Text, ddlRegGender.SelectedItem.Text, txtRegAddress.Text, txtRegEmail.Text); Response.Write("Record was successfully added!"); ClearControls(Page); } else { Response.Write("Email did not match"); txtRegEmail.Focus(); } } public static void ClearControls(Control Parent) { if (Parent is TextBox) { (Parent as TextBox).Text = string.Empty; } else { foreach (Control c in Parent.Controls) ClearControls(c); } } }

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Jboss 5.1.0: java.lang.LinkageError: loader constraint violation for class javax.sql.DataSource

- by lawrencexu

have read quite a lot about this error, the reason is 1) more than one jar containing this class have been include into the classpath, 2)include the jar twice or more, but in my case, this class is jdk class, and I have search no this class have been found under my application. any clue would be very helpful. exception stack: 2012-10-31 14:09:58,319 WARN [org.jboss.detailed.classloader.ClassLoaderManager] (http-0.0.0.0-8080-1:) Unexpected error during load of:javax.sql.DataSource java.lang.LinkageError: loader constraint violation: loader (instance of org/jboss/classloader/spi/base/BaseClassLoader) previously initiated loading for a different type with name "javax/sql/DataSource" at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631) at java.lang.ClassLoader.defineClass(ClassLoader.java:615) at org.jboss.classloader.spi.base.BaseClassLoader.access$200(BaseClassLoader.java:67) at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:633) at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:592) at java.security.AccessController.doPrivileged(Native Method) at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:591) at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:568) at org.jboss.classloader.spi.base.BaseDelegateLoader.loadClass(BaseDelegateLoader.java:135) at org.jboss.classloader.spi.filter.FilteredDelegateLoader.loadClass(FilteredDelegateLoader.java:131) at org.jboss.classloader.spi.base.ClassLoadingTask$ThreadTask.run(ClassLoadingTask.java:455) at org.jboss.classloader.spi.base.ClassLoaderManager.nextTask(ClassLoaderManager.java:267) at org.jboss.classloader.spi.base.ClassLoaderManager.process(ClassLoaderManager.java:166) at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:287) at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:1163) at org.jboss.classloader.spi.base.BaseClassLoader.loadClassFromDomain(BaseClassLoader.java:862) at org.jboss.classloader.spi.base.BaseClassLoader.doLoadClass(BaseClassLoader.java:502) at org.jboss.classloader.spi.base.BaseClassLoader.loadClass(BaseClassLoader.java:447) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) at com.lombardrisk.webgui.dwr.ajax_search.UmbrellaNettingFundsSearch.getBranchesByAgreementId(UmbrellaNettingFundsSearch.java:199) at com.lombardrisk.webgui.dwr.ajax_search.UmbrellaNettingFundsSearch.buildConditionOfPrinAndCpty(UmbrellaNettingFundsSearch.java:177) at com.lombardrisk.webgui.dwr.ajax_search.UmbrellaNettingFundsSearch.getFunds(UmbrellaNettingFundsSearch.java:58) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.directwebremoting.impl.ExecuteAjaxFilter.doFilter(ExecuteAjaxFilter.java:34) at org.directwebremoting.impl.DefaultRemoter$1.doFilter(DefaultRemoter.java:428) at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:431) at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:283) at org.directwebremoting.servlet.PlainCallHandler.handle(PlainCallHandler.java:52) at org.directwebremoting.servlet.UrlProcessor.handle(UrlProcessor.java:101) at org.directwebremoting.servlet.DwrServlet.doPost(DwrServlet.java:146) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at com.lombardrisk.webgui.filter.ValidRequestFilter.doFilter(ValidRequestFilter.java:41) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:183) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:95) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.internalProcess(ActiveRequestResponseCacheValve.java:74) at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:47) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:599) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:451) at java.lang.Thread.run(Thread.java:662)

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User preferences using SQL and JavaScript

- by Shyam

Hi, I am using Server Side JavaScript - yes, I am actually using Server Side JavaScript. To complexify things even more, I use Oracle as a backend database (10g). With some crazy XSLT and mutant-like HTML generation, I can build really fancy web forms - yes, I am aware of Rails and other likewise frameworks and I choose the path of horror instead. I have no JQuery or other fancy framework at my disposal, just plain ol' JavaScript that should be supported by the underlying engine called Mozilla Rhino. Yes, it is insane and I love it. So, I have a bunch of tables at my disposal and some of them are filled with associative keys that link to values. As I am a people pleaser, I want to add some nifty user-preference driven solutions. My users have all an unique user_id and this user_id is available during the entire session. My initial idea is to have a user preference table, where I have "three" columns: user_id, feature and pref_string. Using a delimiter, such as : or - (haven't thought about a suitable one yet), I could like store a bunch of preferences as a list and store its elements inside an array using the .split-method (similar like the PHP-explode function). The feature column could be like the table name or some identifier for the "feature" i want to link preferences too. I hate hardcoding objects, especially as I want to be able to back these up and reuse this functionality application-wide. Of course I would love better ideas, just keep in mind I cannot just add a library that easily. These preferences could be like "joined" to the table, so I can query it and use its values. I hope it doesn't sounds too complex, because well.. its basically something really simple I need. Thanks!

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Fluent Nhibernate - how do i specify table schemas when auto generating tables in SQL CE 4

- by daffers

I am using SQL CE as a database for running local and CI integration tests (normally our site runs on normal SQL server). We are using Fluent Nhibernate for our mapping and having it create our schema from our Mapclasses. There are only two classes with a one to many relationship between them. In our real database we use a non dbo schema. The code would not work with this real database at first until i added schema names to the Table() methods. However doing this broke the unit tests with the error... System.Data.SqlServerCe.SqlCeException : There was an error parsing the query. [ Token line number = 1,Token line offset = 26,Token in error = User ] These are the classes and associatad MapClasses (simplified of course) public class AffiliateApplicationRecord { public virtual int Id { get; private set; } public virtual string CompanyName { get; set; } public virtual UserRecord KeyContact { get; private set; } public AffiliateApplicationRecord() { DateReceived = DateTime.Now; } public virtual void AddKeyContact(UserRecord keyContactUser) { keyContactUser.Affilates.Add(this); KeyContact = keyContactUser; } } public class AffiliateApplicationRecordMap : ClassMap<AffiliateApplicationRecord> { public AffiliateApplicationRecordMap() { Schema("myschema"); Table("Partner"); Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.CompanyName, "Name"); References(x => x.KeyContact) .Cascade.All() .LazyLoad(Laziness.False) .Column("UserID"); } } public class UserRecord { public UserRecord() { Affilates = new List<AffiliateApplicationRecord>(); } public virtual int Id { get; private set; } public virtual string Forename { get; set; } public virtual IList<AffiliateApplicationRecord> Affilates { get; set; } } public class UserRecordMap : ClassMap<UserRecord> { public UserRecordMap() { Schema("myschema"); Table("[User]");//Square brackets required as user is a reserved word Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Forename); HasMany(x => x.Affilates); } } And here is the fluent configuraton i am using .... public static ISessionFactory CreateSessionFactory() { return Fluently.Configure() .Database( MsSqlCeConfiguration.Standard .Dialect<MsSqlCe40Dialect>() .ConnectionString(ConnectionString) .DefaultSchema("myschema")) .Mappings(m => m.FluentMappings.AddFromAssembly(typeof(AffiliateApplicationRecord).Assembly)) .ExposeConfiguration(config => new SchemaExport(config).Create(false, true)) .ExposeConfiguration(x => x.SetProperty("connection.release_mode", "on_close")) //This is included to deal with a SQLCE issue http://stackoverflow.com/questions/2361730/assertionfailure-null-identifier-fluentnh-sqlserverce .BuildSessionFactory(); } The documentation on this aspect of fluent is pretty weak so any help would be appreciated

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Self referencing update SQL statement for Informix

- by CheeseConQueso

Need some Informix SQL... Courses get a regular grade, but their associated labs get a grade of 'LAB'. I need to update the table so that the lab grade matches the course grade. Also, if there is no corresponding course for a lab, it means the course was canceled. In that case, I want to place a flag value of 'X' for its grade. Example data before update: id yr sess crs_no hrs grd 725 2009 FA COLL101 3.000000000000 C 725 2009 FA ENGL021 3.000000000000 FI 725 2009 FA ENGL021L 1.000000000000 LAB 725 2009 FA ENGL031 3.000000000000 FNI 725 2009 FA ENGL031L 1.000000000000 LAB 725 2009 FA MATH010 3.000000000000 FNI 725 2010 SP AOTE101 3.000000000000 C 725 2010 SP ENGL021L 1.000000000000 LAB 725 2010 SP ENGL031 3.000000000000 FI 725 2010 SP ENGL031L 1.000000000000 LAB 725 2010 SP MATH010 3.000000000000 FNI 726 2010 SP SPAN101 3.000000000000 FN Example data after update: id yr sess crs_no hrs grd 725 2009 FA COLL101 3.000000000000 C 725 2009 FA ENGL021 3.000000000000 FI 725 2009 FA ENGL021L 1.000000000000 FI 725 2009 FA ENGL031 3.000000000000 FNI 725 2009 FA ENGL031L 1.000000000000 FNI 725 2009 FA MATH010 3.000000000000 FNI 725 2010 SP AOTE101 3.000000000000 C 725 2010 SP ENGL021L 1.000000000000 X 725 2010 SP ENGL031 3.000000000000 FI 725 2010 SP ENGL031L 1.000000000000 FI 725 2010 SP MATH010 3.000000000000 FNI 726 2010 SP SPAN101 3.000000000000 FN I worked out a solution for this, but it required a lot of on-the-fly composite foreign keys built from concatenating the id, yr, sess, and substring'd crs_no. My solution is not only overkill, but it has gaps in it and it takes too long to process. I know there is an easier way to do this, but I've gone so far down one road that I am having trouble thinking of a different approach.

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Getting code-first Entity Framework to build tables on SQL Azure

- by NER1808

I am new the code-first Entity Framework. I have tried a few things now, but can't get EF to construct any tables in the my SQL Azure database. Can anyone advise of some steps and settings I should check. The membership provider has no problems create it's tables. I have added the PersistSecurityInfo=True in the connection string. The connection string is using the main user account for the server. When I implement the tables in the database using sql everything works fine. I have the following in the WebRole.cs //Initialize the database Database.SetInitializer<ReykerSCPContext>(new DbInitializer()); My DbInitializer (which does not get run before I get a "Invalid object name 'dbo.ClientAccountIFAs'." when I try to access the table for the first time. Sometime after startup. public class DbInitializer:DropCreateDatabaseIfModelChanges<ReykerSCPContext> { protected override void Seed(ReykerSCPContext context) { using (context) { //Add Doc Types context.DocTypes.Add(new DocType() { DocTypeId = 1, Description = "Statement" }); context.DocTypes.Add(new DocType() { DocTypeId = 2, Description = "Contract note" }); context.DocTypes.Add(new DocType() { DocTypeId = 3, Description = "Notification" }); context.DocTypes.Add(new DocType() { DocTypeId = 4, Description = "Invoice" }); context.DocTypes.Add(new DocType() { DocTypeId = 5, Description = "Document" }); context.DocTypes.Add(new DocType() { DocTypeId = 6, Description = "Newsletter" }); context.DocTypes.Add(new DocType() { DocTypeId = 7, Description = "Terms and Conditions" }); //Add ReykerAccounttypes context.ReykerAccountTypes.Add(new ReykerAccountType() { ReykerAccountTypeID = 1, Description = "ISA" }); context.ReykerAccountTypes.Add(new ReykerAccountType() { ReykerAccountTypeID = 2, Description = "Trading" }); context.ReykerAccountTypes.Add(new ReykerAccountType() { ReykerAccountTypeID = 3, Description = "SIPP" }); context.ReykerAccountTypes.Add(new ReykerAccountType() { ReykerAccountTypeID = 4, Description = "CTF" }); context.ReykerAccountTypes.Add(new ReykerAccountType() { ReykerAccountTypeID = 5, Description = "JISA" }); context.ReykerAccountTypes.Add(new ReykerAccountType() { ReykerAccountTypeID = 6, Description = "Direct" }); context.ReykerAccountTypes.Add(new ReykerAccountType() { ReykerAccountTypeID = 7, Description = "ISA & Direct" }); //Save the changes context.SaveChanges(); } and my DBContext class looks like public class ReykerSCPContext : DbContext { //set the connection explicitly public ReykerSCPContext():base("ReykerSCPContext"){} //define tables public DbSet<ClientAccountIFA> ClientAccountIFAs { get; set; } public DbSet<Document> Documents { get; set; } public DbSet<DocType> DocTypes { get; set; } public DbSet<ReykerAccountType> ReykerAccountTypes { get; set; } protected override void OnModelCreating(DbModelBuilder modelBuilder) { //Runs when creating the model. Can use to define special relationships, such as many-to-many. } The code used to access the is public List<ClientAccountIFA> GetAllClientAccountIFAs() { using (DataContext) { var caiCollection = from c in DataContext.ClientAccountIFAs select c; return caiCollection.ToList(); } } and it errors on the last line. Help!

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C#: The input stream is not a valid binary format.

- by Mcoroklo

I have a problem with deserializing in C#/ASP.NET, which gives the exact error: The input stream is not a valid binary format. The starting contents (in bytes) are: 41-41-45-41-41-41-44-2F-2F-2F-2F-2F-41-51-41-41-41 ... What I am trying to do I have a structure with 3 classes. I have a class A which is a base class, and then class B and C which are derived from A. I am trying to store random types of B and C in the database using LINQ to SQL, in a column with the type VARCHAR(MAX). I cannot use BINARY as the length is around 15.000. My code... Error is in the LAST codeblock C# Code in Business layer- Storing a record private void AddTraceToDatabase(FightTrace trace) { MemoryStream recieverStream = new MemoryStream(); MemoryStream firedStream = new MemoryStream(); MemoryStream moveStream = new MemoryStream(); BinaryFormatter binaryFormatter = new BinaryFormatter(); binaryFormatter.Serialize(recieverStream,trace.Reciever); binaryFormatter.Serialize(firedStream,trace.FiredBy); binaryFormatter.Serialize(moveStream,trace.Move); string reciever = Convert.ToBase64String(recieverStream.ToArray()); string fired = Convert.ToBase64String(firedStream.ToArray()); string move = Convert.ToBase64String(moveStream.ToArray()); this.dataAccess.AddFightTrace(trace.TraceType.ToString(),reciever,move,fired,trace.DateTime,this.FightId); } C# Code in Data access layer - Storing a record public void AddFightTrace(string type, string reciever, string Move, string firedBy, DateTime firedAt, int fightid) { GameDataContext db = new GameDataContext(); dbFightTrace trace = new dbFightTrace(); trace.TraceType = type; trace.Reciever = reciever; trace.Move = Move; trace.FiredBy = firedBy; trace.FiredAt = firedAt; trace.FightId = fightid; db.dbFightTraces.InsertOnSubmit(trace); db.SubmitChanges(); } C# Code getting the entry in the database public List<dbFightTrace> GetNewTraces(int fightid, DateTime lastUpdate) { GameDataContext db = new GameDataContext(); var data = from d in db.dbFightTraces where d.FightId==fightid && d.FiredAt > lastUpdate select d; return data.ToList(); } C# Factory, converting from LINQ to SQL class to my objects THIS IS HERE THE ERROR COMES public FightTrace CreateTrace(dbFightTrace trace) { TraceType traceType = (TraceType) Enum.Parse(typeof(TraceType), trace.TraceType); BinaryFormatter formatter = new BinaryFormatter(); System.Text.UTF8Encoding enc = new System.Text.UTF8Encoding(); MemoryStream recieverStream = new MemoryStream(enc.GetBytes(trace.Reciever)); recieverStream.Position = 0; MemoryStream firedStream = new MemoryStream(enc.GetBytes(trace.FiredBy)); firedStream.Position = 0; MemoryStream movedStream = new MemoryStream(enc.GetBytes(trace.Move)); movedStream.Position = 0; // THE NEXT LINE HERE CAUSES THE ERROR NPC reciever = formatter.Deserialize(recieverStream) as NPC; Player fired = formatter.Deserialize(firedStream) as Player; BaseAttack attack = formatter.Deserialize(movedStream) as BaseAttack; FightTrace t = new FightTrace(traceType,reciever,attack,fired); t.TraceId = trace.FightTraceId; t.DateTime = trace.FiredAt; return t; } So the error happends when the first Deserialize method is run, with the above error. I have tried several things but I am quite lost on this one.. Thanks! :-)

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Database cache that I'm not aware of?

- by Martin

I'm using asp.net mvc, linq2sql, iis7 and sqlserver express 2008. I get these intermittent server errors, primary key conflicts on insertion. I'm using a different setup on my development computer so I can't debug. After a while they go away. Restarting iis helps. I'm getting the feeling there is cache somewhere that I'm not aware of. Can somebody help me sort out these errors? Cannot insert duplicate key row in object 'dbo.EnquiryType' with unique index 'IX_EnquiryType'. Edits regarding Venemos answer Is it possible that another application is also accessing the same database simultaneously? Yes there is, but not this particular table and no inserts or updates. There is one other table with which I experience the same problem but it has to do with a different part of the model. How often an in what context do you create a new DataContext instance? Only once, using the singleton pattern. Are the primary keys generated by the database or by the application? Database. Which version of ASP.NET MVC and which version of .NET are you using? RC2 and 3.5.

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sql queries slower than expected

- by neubert

Before I show the query here are the relevant table definitions: CREATE TABLE phpbb_posts ( topic_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, poster_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, KEY topic_id (topic_id), KEY poster_id (poster_id), ); CREATE TABLE phpbb_topics ( topic_id mediumint(8) UNSIGNED NOT NULL auto_increment ); Here's the query I'm trying to do: SELECT p.topic_id, p.poster_id FROM phpbb_topics AS t LEFT JOIN phpbb_posts AS p ON p.topic_id = t.topic_id AND p.poster_id <> ... WHERE p.poster_id IS NULL; Basically, the query is an attempt to find all topics where the number of times someone other than the target user has posted in is zero. In other words, the topics where the only person who has posted is the target user. Problem is that query is taking a super long time. My general assumption when it comes to SQL is that JOINs of any are super fast and can be done in no time at all assuming all relevant columns are primary or foreign keys (which in this case they are). I tried out a few other queries: SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id; That returns 353340 pretty quickly. I then do these: SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id AND p.poster_id <> 77198; SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id WHERE p.poster_id <> 77198; And both of those take quite a while (between 15-30 seconds). If I change the < to a = it takes no time at all. Am I making some incorrect assumptions? Maybe my DB is just foobar'd?

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How to emulate a BEFORE DELETE trigger in SQL Server 2005

- by Mark

Let's say I have three tables, [ONE], [ONE_TWO], and [TWO]. [ONE_TWO] is a many-to-many join table with only [ONE_ID and [TWO_ID] columns. There are foreign keys set up to link [ONE] to [ONE_TWO] and [TWO] to [ONE_TWO]. The FKs use the ON DELETE CASCADE option so that if either a [ONE] or [TWO] record is deleted, the associated [ONE_TWO] records will be automatically deleted as well. I want to have a trigger on the [TWO] table such that when a [TWO] record is deleted, it executes a stored procedure that takes a [ONE_ID] as a parameter, passing the [ONE_ID] values that were linked to the [TWO_ID] before the delete occurred: DECLARE @Statement NVARCHAR(max) SET @Statement = '' SELECT @Statement = @Statement + N'EXEC [MyProc] ''' + CAST([one_two].[one_id] AS VARCHAR(36)) + '''; ' FROM deleted JOIN [one_two] ON deleted.[two_id] = [one_two].[two_id] EXEC (@Statement) Clearly, I need a BEFORE DELETE trigger, but there is no such thing in SQL Server 2005. I can't use an INSTEAD OF trigger because of the cascading FK. I get the impression that if I use a FOR DELETE trigger, when I join [deleted] to [ONE_TWO] to find the list of [ONE_ID] values, the FK cascade will have already deleted the associated [ONE_TWO] records so I will never find any [ONE_ID] values. Is this true? If so, how can I achieve my objective? I'm thinking that I'd need to change the FK joining [TWO] to [ONE_TWO] to not use cascades and to do the delete from [ONE_TWO] manually in the trigger just before I manually delete the [TWO] records. But I'd rather not go through all that if there is a simpler way.

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insert xml into sql server

- by JonDog

ok, so I know there are a bunch of other post on importing xml to sql server but I just cant seem to figure it out. I think my problem may have to do with having multi-levels. Can anyone help please. My xml, sql table, and the code i've tried. thanks in advance. <items> <item> <sku> <value> the_sku </value> </sku> <short_dis2> <value> short_discription2 <value/> </short_dis2> <short_dis1> <value> short_discription1 </value> </short_dis1> <title> <value> product_title </value> </title> <detailSpec> <value> detailed_specification_html </value> </detailSpec> <basicSpec> <value> basic_overview_html </value> </basicSpec> <basicSpecHeading> <value> besic_spec_heading </value> </basicSpecHeading> <detailSpecHeading> <value> detailed_specifications_heading </value> </detailSpecHeading> <model> <value> the_model_number </value> </model> <image_file_name> <value> the_image_url </value> </image_file_name> </item> ... CREATE TABLE [dbo].[products]( [sku] [nchar](15) NOT NULL, [model] [nvarchar](50) NULL, [title] [ntext] NULL, [short_dis1] [ntext] NULL, [short_dis2] [ntext] NULL, [basicSpecHeading] [ntext] NULL, [basicSpec] [ntext] NULL, [detailSpecHeading] [ntext] NULL, [detailSpec] [ntext] NULL, [image_file_name] [nchar](100) NULL INSERT INTO products (sku, short_dis2,short_dis1,title,detailSpec,basicSpec,basicSpecHeading,detailSpecHeading,model,image_file_name) SELECT X.product.query('sku').value('.', 'nchar(15)'), X.product.query('short_dis2').value('.', 'nvarchar(max)'), X.product.query('short_dis1').value('.', 'nvarchar(max)'), X.product.query('title').value('.', 'nvarchar(max)'), X.product.query('detailSpec').value('.', 'nvarchar(max)'), X.product.query('basicSpec').value('.', 'nvarchar(max)'), X.product.query('basicSpecHeading').value('.', 'nvarchar(max)'), X.product.query('detailSpecHeading').value('.', 'nvarchar(max)'), X.product.query('model').value('.', 'nvarchar(max)'), X.product.query('image_file_name').value('.', 'nvarchar(max)') FROM ( SELECT CAST(x AS XML) FROM OPENROWSET( BULK 'C:\users\me\desktop\xml_sample.xml', SINGLE_BLOB) AS T(x) ) AS T(x) CROSS APPLY x.nodes('Products/Product') AS X(product);

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SQL inner join from field defined table?

- by Wolftousen

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Bob Dorr’s SQL I/O Presentation on PSS Blog

- by Jonathan Kehayias

In case you missed it, Bob Dorr from the PSS Team posted an amazing blog post today yesterday with all of the slides and speaker notes from his SQL Server I/O presentation. This is a must read for and Database Professional using SQL Server. http://blogs.msdn.com/psssql/archive/2010/03/24/how-it-works-bob-dorr-s-sql-server-i-o-presentation.aspx Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!...(read more)

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Bob Dorr’s SQL I/O Presentation on PSS Blog

- by Jonathan Kehayias

In case you missed it, Bob Dorr from the PSS Team posted an amazing blog post today yesterday with all of the slides and speaker notes from his SQL Server I/O presentation. This is a must read for and Database Professional using SQL Server. http://blogs.msdn.com/psssql/archive/2010/03/24/how-it-works-bob-dorr-s-sql-server-i-o-presentation.aspx Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!...(read more)

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Troubleshooting Application Timeouts in SQL Server

- by Tara Kizer

I recently received the following email from a blog reader: "We are having an OLTP database instance, using SQL Server 2005 with little to moderate traffic (10-20 requests/min). There are also bulk imports that occur at regular intervals in this DB and the import duration ranges between 10secs to 1 min, depending on the data size. Intermittently (2-3 times in a week), we face an issue, where queries get timed out (default of 30 secs set in application). On analyzing, we found two stored procedures, having queries with multiple table joins inside them of taking a long time (5-10 mins) in getting executed, when ideally the execution duration ranges between 5-10 secs. Execution plan of the same displayed Clustered Index Scan happening instead of Clustered Index Seek. All required Indexes are found to be present and Index fragmentation is also minimal as we Rebuild Indexes regularly alongwith Updating Statistics. With no other alternate options occuring to us, we restarted SQL server and thereafter the performance was back on track. But sometimes it was still giving timeout errors for some hits and so we also restarted IIS and that stopped the problem as of now." Rather than respond directly to the blog reader, I thought it would be more interesting to share my thoughts on this issue in a blog. There are a few things that I can think of that could cause abnormal timeouts: Blocking Bad plan in cache Outdated statistics Hardware bottleneck To determine if blocking is the issue, we can easily run sp_who/sp_who2 or a query directly on sysprocesses (select * from master..sysprocesses where blocking <> 0). If blocking is present and consistent, then you'll need to determine whether or not to kill the parent blocking process. Killing a process will cause the transaction to rollback, so you need to proceed with caution. Killing the parent blocking process is only a temporary solution, so you'll need to do more thorough analysis to figure out why the blocking was present. You should look into missing indexes and perhaps consider changing the database's isolation level to READ_COMMITTED_SNAPSHOT. The blog reader mentions that the execution plan shows a clustered index scan when a clustered index seek is normal for the stored procedure. A clustered index scan might have been chosen either because that is what is in cache already or because of out of date statistics. The blog reader mentions that bulk imports occur at regular intervals, so outdated statistics is definitely something that could cause this issue. The blog reader may need to update statistics after imports are done if the imports are changing a lot of data (greater than 10%). If the statistics are good, then the query optimizer might have chosen to scan rather than seek in a previous execution because the scan was determined to be less costly due to the value of an input parameter. If this parameter value is rare, then its execution plan in cache is what we call a bad plan. You want the best plan in cache for the most frequent parameter values. If a bad plan is a recurring problem on your system, then you should consider rewriting the stored procedure. You might want to break up the code into multiple stored procedures so that each can have a different execution plan in cache. To remove a bad plan from cache, you can recompile the stored procedure. An alternative method is to run DBCC FREEPROCACHE which drops the procedure cache. It is better to recompile stored procedures rather than dropping the procedure cache as dropping the procedure cache affects all plans in cache rather than just the ones that were bad, so there will be a temporary performance penalty until the plans are loaded into cache again. To determine if there is a hardware bottleneck occurring such as slow I/O or high CPU utilization, you will need to run Performance Monitor on the database server. Hopefully you already have a baseline of the server so you know what is normal and what is not. Be on the lookout for I/O requests taking longer than 12 milliseconds and CPU utilization over 90%. The servers that I support typically are under 30% CPU utilization, but your baseline could be higher and be within a normal range. If restarting the SQL Server service fixes the problem, then the problem was most likely due to blocking or a bad plan in the procedure cache. Rather than restarting the SQL Server service, which causes downtime, the blog reader should instead analyze the above mentioned things. Proceed with caution when restarting the SQL Server service as all transactions that have not completed will be rolled back at startup. This crash recovery process could take longer than normal if there was a long-running transaction running when the service was stopped. Until the crash recovery process is completed on the database, it is unavailable to your applications. If restarting IIS fixes the problem, then the problem might not have been inside SQL Server. Prior to taking this step, you should do analysis of the above mentioned things. If you can think of other reasons why the blog reader is facing this issue a few times a week, I'd love to hear your thoughts via a blog comment.

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