Nhibernate creating unusual SQL for a basic Query

Question

The following is from the open source project Funnelweb. I am in the process of converting it from SQL Express to SQL CE 4.0. The SQL that is sent to the database contains logical OR ( || ). This results in the SQL error. Can anyboy explain why this would be happening?

FLuenbt Nhibernate Mapping

public class TagMapping : ClassMap<Tag>
    {
        public TagMapping()
        {
            Id(x => x.Id);
            Map(x => x.Name);
            HasManyToMany(x => x.Entries)
                .Table("TagItem")
                .ParentKeyColumn("TagId")
                .ChildKeyColumn("EntryId")
                .AsSet()
                .Inverse()
                .LazyLoad();
        }
    }


public IQueryable<Tag> GetTags(string tagName)
        {
            tagName = tagName ?? string.Empty;

            return from tag in session.Query<Tag>()
                   where tag.Name.Contains(tagName)
                   select tag;

        }

SQL that it sent to query the database

select tag0_.Id as Id7_, tag0_.Name as Name7_ from "Tag" tag0_ where tag0_.Name like ('%'||@p0||'%')

Stack Trace

NHibernate.Exceptions.GenericADOException was unhandled by user code
  Message=could not execute query
[ select tag0_.Id as Id7_, tag0_.Name as Name7_ from "Tag" tag0_ where tag0_.Name like ('%'||@p0||'%') ]
  Name:p1 - Value:
[SQL: select tag0_.Id as Id7_, tag0_.Name as Name7_ from "Tag" tag0_ where tag0_.Name like ('%'||@p0||'%')]
  Source=NHibernate
  SqlString=select tag0_.Id as Id7_, tag0_.Name as Name7_ from "Tag" tag0_ where tag0_.Name like ('%'||@p0||'%')
  StackTrace:
       at NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters)
       at NHibernate.Loader.Loader.ListIgnoreQueryCache(ISessionImplementor session, QueryParameters queryParameters)
       at NHibernate.Loader.Loader.List(ISessionImplementor session, QueryParameters queryParameters, ISet`1 querySpaces, IType[] resultTypes)
       at NHibernate.Hql.Ast.ANTLR.Loader.QueryLoader.List(ISessionImplementor session, QueryParameters queryParameters)
       at NHibernate.Hql.Ast.ANTLR.QueryTranslatorImpl.List(ISessionImplementor session, QueryParameters queryParameters)
       at NHibernate.Engine.Query.HQLQueryPlan.PerformList(QueryParameters queryParameters, ISessionImplementor session, IList results)
       at NHibernate.Impl.SessionImpl.List(IQueryExpression queryExpression, QueryParameters queryParameters, IList results)
       at NHibernate.Impl.SessionImpl.List(IQueryExpression queryExpression, QueryParameters parameters)
       at NHibernate.Impl.ExpressionQueryImpl.List()
       at NHibernate.Linq.NhQueryProvider.ExecuteQuery(NhLinqExpression nhLinqExpression, IQuery query, NhLinqExpression nhQuery)
       at NHibernate.Linq.NhQueryProvider.Execute(Expression expression)
       at NHibernate.Linq.NhQueryProvider.Execute[TResult](Expression expression)
       at Remotion.Data.Linq.QueryableBase`1.GetEnumerator()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at FunnelWeb.Web.Areas.Admin.Views.WikiAdmin.EditModel..ctor(PageName page, Int32 originalEntryId, IEnumerable`1 tags) in C:\Projects\oss\funnelweb\src\FunnelWeb.Web\Areas\Admin\Views\WikiAdmin\EditModel.cs:line 24
       at FunnelWeb.Web.Areas.Admin.Controllers.WikiAdminController.Edit(PageName page, Nullable`1 revertToRevision) in C:\Projects\oss\funnelweb\src\FunnelWeb.Web\Areas\Admin\Controllers\WikiAdminController.cs:line 52
       at lambda_method(Closure , ControllerBase , Object[] )
       at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
       at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
       at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12()
       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
  InnerException: System.Data.SqlServerCe.SqlCeException
       Message=There was an error parsing the query. [ Token line number = 1,Token line offset = 91,Token in error = | ]
       Source=SQL Server Compact ADO.NET Data Provider
       ErrorCode=-2147467259
       HResult=-2147217900
       NativeError=25501
       StackTrace:
            at System.Data.SqlServerCe.SqlCeCommand.ProcessResults(Int32 hr)
            at System.Data.SqlServerCe.SqlCeCommand.CompileQueryPlan()
            at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommand(CommandBehavior behavior, String method, ResultSetOptions options)
            at System.Data.SqlServerCe.SqlCeCommand.ExecuteReader(CommandBehavior behavior)
            at System.Data.SqlServerCe.SqlCeCommand.ExecuteDbDataReader(CommandBehavior behavior)
            at System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader()
            at NHibernate.AdoNet.AbstractBatcher.ExecuteReader(IDbCommand cmd)
            at NHibernate.Loader.Loader.GetResultSet(IDbCommand st, Boolean autoDiscoverTypes, Boolean callable, RowSelection selection, ISessionImplementor session)
            at NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies)
            at NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies)
            at NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters)
       InnerException: 

Answer 1

Try subclassing the MsSqlCe[40]Dialect and adding the following line in the constructor:

RegisterFunction("concat",
                 new VarArgsSQLFunction(NHibernateUtil.String, "(", "+", ")"));

If it works, please open a Jira ticket (http://jira.nhforge.org) with it as a patch to MsSqlCeDialect.