I tend to go for this pattern: public class DogWithBreed { public Dog Dog { get; set; } public string BreedName { get; set; } } public IQueryable<DogWithBreed> GetDogsWithBreedNames() { var db = new DogDataContext(ConnectString); var result = from d in db.Dogs join b in db.Breeds on d.BreedId equals b.BreedId select new DogWithBreed() { Dog … Read more
var result = from sc in enumerableOfSomeClass join soc in enumerableOfSomeOtherClass on sc.Property1 equals soc.Property2 select new { SomeClass = sc, SomeOtherClass = soc }; Would be equivalent to: var result = enumerableOfSomeClass .Join(enumerableOfSomeOtherClass, sc => sc.Property1, soc => soc.Property2, (sc, soc) => new { SomeClass = sc, SomeOtherClass = soc }); As you can … Read more
There are three ways to keep the model in sync. Delete the modified tables from the designer, and drag them back onto the designer surface from the Database Explorer. I have found that, for this to work reliably, you have to: a. Refresh the database schema in the Database Explorer (right-click, refresh) b. Save the … Read more
try using the Date property on the DateTime Object… if(dtOne.Date == dtTwo.Date) ….
Try using the ToDictionary method like so: var dict = TableObj.Select( t => new { t.Key, t.TimeStamp } ) .ToDictionary( t => t.Key, t => t.TimeStamp );
First off, if you’re starting a new project, go with Entity Framework (“EF”) – it now generates much better SQL (more like Linq to SQL does) and is easier to maintain and more powerful than Linq to SQL (“L2S”). As of the release of .NET 4.0, I consider Linq to SQL to be an obsolete … Read more
It goes something like: from t1 in db.Table1 join t2 in db.Table2 on t1.field equals t2.field select new { t1.field2, t2.field3} It would be nice to have sensible names and fields for your tables for a better example. 🙂 Update I think for your query this might be more appropriate: var dealercontacts = from contact … Read more
If your result set returns 0 records: SingleOrDefault returns the default value for the type (e.g. default for int is 0) FirstOrDefault returns the default value for the type If you result set returns 1 record: SingleOrDefault returns that record FirstOrDefault returns that record If your result set returns many records: SingleOrDefault throws an exception … Read more
LINQ to SQL only supports 1 to 1 mapping of database tables, views, sprocs and functions available in Microsoft SQL Server. It’s a great API to use for quick data access construction to relatively well designed SQL Server databases. LINQ2SQL was first released with C# 3.0 and .Net Framework 3.5. LINQ to Entities (ADO.Net Entity … Read more
Yes, both will give you deferred execution. The difference is that IQueryable<T> is the interface that allows LINQ-to-SQL (LINQ.-to-anything really) to work. So if you further refine your query on an IQueryable<T>, that query will be executed in the database, if possible. For the IEnumerable<T> case, it will be LINQ-to-object, meaning that all objects matching … Read more