2016年1月11日 · linq query with or and operator together. 0. LINQ select with more than one condition using OR. 1. Linq ...

2015年4月27日 · When this is a linq-to-object call, multiple where clauses will lead to a chain of IEnumerables that read from each other. Using the single-clause form will help performance here. When the underlying provider translates it into a SQL statement, the chances are good that both variants will create the same statement.

LINQ To Entities - examine the System.Data.Objects namespace. Especially note the ObjectContext. This is a DataAccess technology built by the ADO.NET team. It is complex, powerful, and harder to use than LINQ To SQL. LINQ To XML - examine the System.Xml.Linq namespace. Essentially, people weren't satisfied with the stuff in System.Xml. So ...

2011年6月2日 · Is it possible to use If Else conditional in a LINQ query? Something like from p in db.products if p.price>0 select new { Owner=from q in db.Users select q.Name } else select new {

2008年8月14日 · This construct includes the 'or' part of the expression in the generated SQL query. The accepted answer will generate more efficient statements. Depending on the data provider's optimizations, of course. LINQ-to-SQL may have better optimization, but LINQ-to-Entities doesn't. –

2009年6月6日 · There's only mileage in writing the extension class if you're going to be reusing the Where In part of your linq. Upvoted the answer, but just wanted to let others who come across this question and go straight for the extension method route. –

2013年2月1日 · But against an SQL database, your LINQ code will be compiled into an expression tree, analysed and translated into an SQL command. This functionality has no concept of custom-made extension methods or methods of other objects like .Contains(...). It could be easily implemented into the standard LINQ-To-SQL functionality by Microsoft though.

This Linq query is the same as the following SQL: SELECT Items.* FROM TagMaps INNER JOIN Items ON Item.ItemId = TagMap.ItemId WHERE TagMaps.TagId IN (12,32,24) Linq takes care of the INNER JOIN part for you, because it knows how to go from TagMap to Item. –

2010年9月10日 · This is how can you can do it with the noob Linq syntax. This applies the condition3 only if condition2 is false. If condition2 is true, you are essentially doing && true which has no effect on the where clause. So it is essentially doing this:

2011年3月21日 · In native LINQ you may use combination of Contains/StartsWith/EndsWith or RegExp. In LINQ2SQL use method SqlMethods.Like() from i in db.myTable where SqlMethods.Like(i.field, "tra%ata") select i add Assembly: System.Data.Linq (in System.Data.Linq.dll) to use this feature.