LINQ syntax Details

For each search result set, I came out in three ways to get a better understanding.
1. Simple LINQ Syntax

1var SS = from R in Db. Am_recproscheme Select R;//2var SS1 = db. am_recproscheme;//3string sssql = "SELECT * from Am_recproscheme";

2. Query with where

1var SS = from R in Db. Am_recproscheme where r.rpid > select R;//2var SS1 = db. Am_recproscheme.where (p = p.rpid >)//3string sssql = "SELECT * from Am_recproscheme Where rpid>10";

3. Simple function calculation (count,min,max,sum)

1////gets the largest rpid//var SS = (from R in Db. Am_recproscheme Select R). Max (p = = p.rpid);////gets the smallest rpid//var SS = (from R in Db. Am_recproscheme Select R). Min (p = p.rpid);//Gets the total number of result sets//var SS = (from R in Db. Am_recproscheme Select R). Count ();//Get rpid and var ss = (from R in Db. Am_recproscheme Select R). Sum (p = = p.rpid);//2//var SS1 = db. Am_recproscheme.max (p=>p.rpid);//var SS1 = db. Am_recproscheme.min (p = p.rpid);//var SS1 = db. Am_recproscheme.count (); var SS1 = db. Am_recproscheme.sum (p = p.rpid); Response.Write (ss);//3string sssql = "Select Max (rpid) from Am_recproscheme", Sssql = "Select min (rpid) from Am_recprosche Me "; sssql =" SELECT count (1) from Am_recproscheme ", Sssql =" select sum (rpid) from Am_recproscheme ";

4. Sort ORDER BY Desc/asc

var ss = from R in Db. Am_recproscheme where r.rpid >         r.rpid Descending  //reverse order/         /by R.rpid ascending   //         Select r;//Positive-order var SS1 = db. Am_recproscheme.orderby (p = p.rpid). Where (p = p.rpid > 10). ToList ();//reverse var SS2 = db. Am_recproscheme.orderbydescending (p = p.rpid). Where (p = p.rpid > 10). ToList (); String sssql = "SELECT * from Am_recproscheme where rpid>10 order by Rpid [DESC|ASC]";

5.top (1)

If the last one can be sorted in flashbacks, then the value var ss = (from R in DB). Am_recproscheme Select R). FirstOrDefault ();//() LINQ to EF does not seem to support last () var SS1 = db. Am_recproscheme.firstordefault ();//var SS1 = db. Am_recproscheme.first ();          String sssql = "SELECT Top (1) * from Am_recproscheme";

6. Skip the previous number of data to take the remaining data

1var SS = (from R in Db. Am_recproscheme          r.rpid Descending          Select R). Skip (10); Skip the first 10 data and fetch all the data after 10   //2  var ss1 = db. Am_recproscheme.orderbydescending (p = p.rpid). Skip (10). ToList ();//3string sssql = "SELECT * from  (select Row_number () over (order by rpid Desc) as RowNum, * from [Am_recprosch EME]) as T where rownum>10 ";

7. Paging Data Query

1var SS = (from R in Db. Am_recproscheme          where r.rpid >          r.rpid descending          Select R). Skip (10). Take (10); Takes 11th to 20th data//2 take                   (10): Data is obtained from the beginning, obtaining a specified number (10) of continuous data var SS1 = db. Am_recproscheme.orderbydescending (p = p.rpid). Where (p = p.rpid > 10). Skip (10). Take (10). ToList ();//3string sssql = "SELECT * from  (select Row_number () over (order by rpid Desc) as RowNum, * from [Am_recprosch EME]) as T where rownum>10 and rownum<=20 ";

8. Include, like '% '

1var SS = from R in Db. Am_recproscheme         where R.sortstext.contains ("Zhang")         select R;//2var SS1 = db. Am_recproscheme.where (p = p.sortstext.contains ("Zhang")). ToList ();//3string sssql = "SELECT * from Am_recproscheme where sortstext like '% Zhang% '";

9. Group by

1var SS = from R in Db.             Am_recproscheme r.rpid Descending Group R by R.rectype into n select new { N.key,//This Key is rectype rpid = n.sum (r = r.rpid),//group rpid and maxrpid = N.max (r = R.RP ID),//group max Rpid minrpid = n.min (r = r.rpid),//Group min rpid};foreach (Var t in ss) {Response.Write ( T.key + "--" + T.rpid + "--" + T.maxrpid + "--" + T.minrpid);} 2var SS1 = from R in Db. Am_recproscheme r.rpid Descending Group R by R.rectype into n select N;foreach (Var t i N SS1) {Response.Write (T.key + "--" + t.min (p = = p.rpid));} 3var SS2 = db. Am_recproscheme.groupby (p = p.rectype); foreach (Var t in Ss2) {Response.Write (T.key + "--" + t.min (p = p.rpid)) ;} 4string sssql = "Select Rectype,min (rpid), Max (rpid), sum (rpid) from Am_recproscheme Group by RecType";

10. Connection Query

1var SS = from R in Db. Am_recproscheme         join W in DB. Am_test_result on R.rpid equals w.rsid by         r.rpid descending         Select R;//2var SS1 = db. Am_recproscheme.join (db. Am_test_result, p = p.rpid, r = R.rsid, (p, r) = p). OrderByDescending (p = p.rpid). ToList ();//3string sssql = "Select r.* from  [Am_recproscheme] as R inner join [dbo].[ Am_test_result] as T on r.[rpid] = T.[rsid] ORDER by r.[rpid] desc ";

in of 11.sql

1var SS = from P in db. Am_recproscheme         where (new int?[] {24, 25,26}). Contains (p.rpid)         select P;foreach (Var p in ss) {    Response.Write (p.sorts);} 2string st = "SELECT * from Am_recproscheme where rpid in (24,25,26)";

Learning these ten common query tags, plus the view, will basically solve most of the query problems.

There seems to be a tool for SQL to LINQ, Linqer Lingpad.

LINQ syntax Details