convert sql query to linq lambda expression

Label:The writing format for LINQ is as follows:From Temp variable in collection object or database objectWhere Condition expression[ORDER BY condition]The value queried in the Select Temp variable[GROUP BY conditions] The lambda expression is written in the following format: (parameter list) = =

3 courses. SelectAVG (degree) fromScorewhereCNO like'3%'GROUP BY Cno have Count (*) >=5Linq: fromSinchScoreswhereS.cno. StartsWith ("3") group S by s.cno into CCwhereCc. Count () >=5 SelectCc. Average (c =C.degree) Lambda:Scores.Where (S= = S.cno. StartsWith ("3") ) . GroupBy (S=s.cno). Where (CC= = (CC. Count () >=5) ) . Select (CC= CC. Average (c =C.degree)) Linq:sqlmethod like can also write: S.cno. StartsWith ("3") or Sqlmethods.like (S.cno,"%3") 14. Mult

") View Code 12. Grouping example Code queries the average score of at least 5 students in the score table and 3 courses. SelectAVG (degree) fromScorewhereCNO like'3%'GROUP BY Cno have Count (*) >=5Linq: fromSinchScoreswhereS.cno. StartsWith ("3") group S by s.cno into CCwhereCc. Count () >=5 SelectCc. Average (c =C.degree) Lambda:Scores.Where (S= = S.cno. StartsWith ("3") ) . GroupBy (S=s.cno). Where (CC= = (CC. Count () >=5) ) . Select (CC= CC. Average (c =C

Tags: join outer store BSP using code com URL wwwImplementing a LEFT join using a lambda expression in LINQ to SQL and the Entity frameworkWe know that lambda expressions use the Join function in LINQ to

,sc.degree from course as c,score as SC where c.cno = sc.cnolinq: From C in Courses J Oin SC in Scores on c.cno equals SC. CNO Select New { sc. Sno,c.cname,sc. Degree }lambda: courses.join (Scores, C = c.cno, sc = sc. CNO, (c, sc) = = new { SNO = sc. SNO,

Label:We know that lambda expressions use the Join function in LINQ to SQL and the Entity framework to implement inner joins, so how can you implement a LEFT join in a lambda expression? The trick is to add a function DefaultIfEmpty function to the join, and in fact this fun

, see your own needs}). ToList (); Note:(Photoalbumlistmodel This is my new entity class, because the original query result set is anonymous type, to the page can not be recognized, need to convert, of course, but also using the method of foreach conversion) Of course, there are more than one way, there are other better and more aspects can also leave a message to me, do not understand can also discuss with

Due to some historical reasons, leading to the company's existing projects in the database there are a large number of Chinese table names, the text segment name, and the way to operate the database or SQL statement stitching + ADO, of course, the way to operate the database a little problem, but the most I can not accept is the SQL statement splicing, Because the database in a large number of Chinese table

db.Products where p.UnitsInStock Statement Description: In this example, the direct key expression of the query and key expression is directly calculated as a Dictionary ADO. NET and LINQ to SQL LINQ to

First of all, the three are completely three different things, SQL is Structured Query Language (structured query Language) abbreviation, this is familiar to everyone, the following is mainly about the basic concepts of LINQ and lambda expressions and the same

Document directory Range variable Query expression and method syntax Combined query syntax Another two types of Syntax are available when writing a LINQ Query: Method Syntax (Fluent Syntax) and Query

single expression rather than a complete statement, method, type, and so on, and the benefits are quite limited. Likewise, there is no Expression Tree, and lambda expressions are much less useful. it is still very popular to have a more concise way to create a delegated instance, and a more mathematical development method is also feasible.

I didn't run my blog for half a year. I was not very diligent, I started my own business, and I didn't have time to come. But in this small project, I used LINQ to SQL. In this case, I must search for multiple combinations of conditions. Although I have only a few research on the Expression Tree, it seems that there is no other way to study it. This article is su

This article is suitable for the small amount of data, for large data, need to use another way, see the next First of all, from the Internet search, is essential, probably understand the LINQ multiple conditional combination query direction, began to start, first, write a delegate method: Copy Code code as follows: private bool Getcondition (FeedBack FB) { bool Boolresult = true; int f

This article is suitable for small data volumes. For large data volumes, another method is required. For more information, see the next article.First of all, searching on the internet is essential. After learning about the direction of the Multi-condition combination query of linq, you can start to do it. First, write a delegate method:Copy codeThe Code is as follows:Private bool GetCondition (FeedBack fb){

. SubmitChanges ();Delete data:This data should be checked before deleting the data.Querying through IDs This data returns an objectUsers u = con. Users.where (r=>r.ids.tostring () ==ids). FirstOrDefault ();Where parentheses are followed by the lambda expression R for each row of data,=> is the basic format FirstOrDefault () returns the first data or the return nullIf u is not empty, the database context is

Label:There are currently two tables, Sgroup and Sgroupuser, which are associated by Gkey, while the Sgroup table records the group, and the Sgroupuser record is the user in the group, so there is no data in the Sgroupuser. You need to use the left join to get the data: The LINQ syntax is as follows: var sg = ( from the dc.sgroup in dc.sgroupuser on G.gkey equals Gu.gkey into L from in l.defaultifempty ()

query, and executing the query (2) After a query is defined, the query is actually executed only when enumeration results are required. This method is called "delayed execution ". (3) When the query result returns a single value, the

Label:Three ways: LINQ, LAMBDA, SQL syntax 1. Simple LINQ Syntax 1 var ss = from R in Db. Am_recproscheme Select R; 2 var SS1 = db. Am_recproscheme; 3 String sssql = "SELECT * from Am_recproscheme"; 2.

What is LINQ?? LINQ即Language Integrated Query(语言集成查询)，LINQ是集成到C#和Visual Basic.NET这些语言中用于提供查询数据能力的一个新特性。 Two simple examples of LINQ. (In simple Form I will not introduce, mainly in the form of Lambda int