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This article mainly introduces "what is the method of Linq link". In daily operation, I believe that many people have doubts about the method of Linq link. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the question of "what is the method of Linq link?" Next, please follow the editor to study!

The following is the code for a Linq connection (Group By)

SELECT p.ParentId, COUNT (c.ChildId) FROM ParentTable p LEFT OUTER JOIN ChildTable c ON p.ParentId = c.ChildParentIdGROUP BY p.ParentId

Convert to Linq connection:

(from p in context.ParentTable join c in context.ChildTable on p.ParentId equals c.ChildParentId into J1 from j2 in j1.DefaultIfEmpty () select new {ParentId = p.ParentId, ChildId = j2==null? 0: 1}) .GroupBy (o = > o.ParentId) .Select (o = > new {ParentId = o.key, Count = o.Sum (p = > p.ChildId)})

When connecting to the local database using the connection character Linq, the test using string connectionString = "Server=localhost;uid=sa;pwd=sa;database=DataBase;Integrated Security=SSPI" is normal, but connecting to the remote database throws a "not associated with a trusted SQL Server connection" error. The connection string should be changed to: the "Data Source=192.168.4.23;Initial Catalog=DataBase;Persist Security Info=True;User ID=sa;Password=sa" test passed.

The main reasons are:

(1) user name uid= > User ID

(2) password pwd= > Password

When using ADO.Net for data Linq connection, the requirements in string format are not very strict, while using Linq for database access is more stringent.

By the way, explain the meaning of the connection string attribute:

There are two main attributes about Linq connection:

Persist Security Info attribute means whether to save security information, in fact, it can be simply understood as "whether ADO.Net saves password information after a successful database connection", True means to save, False means not to save. The default is False.

The Integrated Security attribute means whether to use Windows authentication, and Integrated Security = Ture uses windows authentication, but only if Integrated Security = SSPI will apply to the OleDb .NET Framework data provider. Setting Integrated Security=true for ConnectionString throws an exception.

At this point, the study of "what is the method of Linq link" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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