我想做这样的事情:
DataTable q = from c in customers join o in orders on c.Key equals o.Key into outer from j in outer.DefaultIfEmpty() select new { c.*, j.* };我最近得到的是以下内容:
The closest I currently got is the following:
var q = from c in customers join o in orders on c.Key equals o.Key into outer from j in outer.DefaultIfEmpty() select new { c, j };我希望我的结果(q)包含c和j的所有列. c和j都包含很多列,所以我宁愿不这样列出它们:
I'd like my result (q) to have all the columns from c and j. both c and j contain a lot of columns, so I'd rather not list them as such:
select new { c.col1, c.col2, etc. }但是我基本上希望最终的DataTable由c.*和j.*组成.
But I basically want the final DataTable to be made up of c.* and j.*.
如果我在'select new'中指定了所有c和j列,则此答案(不是接受的答案,但下面的答案)有效: 如何将LINQ结果转换为DATATABLE? 但我想避免全部列出.
This answer (not the accepted answer, but the one below it) works if I specify all the c and j columns inside 'select new': How to Convert a LINQ result to DATATABLE? But I'd like to avoid listing them all.
推荐答案首先,我希望手动指定列,因为我想最小化基础层(数据库架构,查询提供程序)对我的应用程序的影响.但是,如果您真的想要执行此操作,则可以通过某种技巧来实现它.
First, I would prefer to specify the columns manually, because I would like to minimize the impact of underlying layers - database schema, query provider - on my application. But if you really want to do this there is a bit of a hacky way to accomplish it.
当您使用实体框架时(首先是数据库):
When your are using entity framework (database first):
var qs = ((ObjectQuery)q).ToTraceString(); var ds = new DataSet(); var da = new SqlDataAdapter(qs, new SqlConnection(((EntityConnection)context.Connection).StoreConnection.ConnectionString)); da.Fill(ds, "Result");这个想法是在实际执行发出的SQL之前捕获它,并使用它填充DataTable(在DataSet中).
The idea is to catch the emitted SQL before it is actually executed and use it to fill a DataTable (in a DataSet).
与Linq-to-sql基本相同,只是获取命令字符串和连接字符串的方式不同:
With Linq-to-sql is is basically the same, just the way to get the command string and connection string is different:
context.GetCommand(q).CommandText context.Connection.ConnectionString以EF代码优先:
q.ToString() context.Database.Connection.ConnectionString更多推荐
加入LINQ可以避免在"new {}"中明确命名属性?
发布评论