Entity framework query, EF execution sql

First, Introduction

EF supports the open bottom of the ADO framework, DbContext has three common methods

Dbset.sqlquery//Queries and returns entitiesdbcontext.database.sqlquery<t>     //Executes a query, and can convert the return set to an object Dbcont Ext. Database.executesqlcommand    //execute a SQL command with no return set, such as Update,delete operation　　

Second, usage

1. Dbset.sqlquery usage

            var list = db.admins.SqlQuery ("SELECT * from admin");            foreach (var item in list)            {                Response.Write (item.username);                Response.Write ("<br>");            }  

2. Dbcontext.database.sqlquery<t> usage

            var list = db. Database.sqlquery<admin> ("SELECT * from admin"). ToList ();            foreach (var item in list)            {                Response.Write (item.username);                Response.Write ("<br>");            }  

3. DbContext.Database.ExecuteSqlCommand Usage

var res=db. Database.executesqlcommand ("Update admin set password= ' 123456 '");            Response.Write (res);

Description:results of 1 and 2 are the same

Iii. Summary

Native SQL execution Query:

Need to return entity model, use Dbset.sqlquery (context Trace, equivalent to LINQ mode)

Need to return other types, using Database.sqlquery

Native SQL to perform the update:

Using Database.executesqlcommand

Iv. examples of common queries

1, EF Select how to get the last 10 days of data

DateTime now = DateTime.Now; var res = db. News.where (p = System.Data.Objects.EntityFunctions.DiffDays (DateTime.Now, P.createtime) <), return Res. Tolist<news> (); 

2. Load ...

Entity framework query, EF execution sql