Learn about Entity Framework Other query methods Sql,raw SQL Analysis

One: LINQ is not a unique query for EF ...

Two: Entity Sql

1. ESQL = Entity SQL ... "Class SQL language" is about the same as SQL, but not SQL ...

using (schooldbentities db = new Schooldbentities ())
{
Querying with Object Services and Entity SQL
String sqlString = "Select Value s from schooldbentities.students as S"; SELECT * FROM Student

var objctx = (db as Iobjectcontextadapter). ObjectContext;

Objectquery<student> Student = objctx. Createquery<student> (sqlString);

var query = student. ToList ();
}

Learn about a grammar ...

Official website: https://msdn.microsoft.com/zh-cn/library/bb399560.aspx

2. Entityconnection,entitycommand ....

Use the soundtrack for a little bit of command

using (var con = new EntityConnection ("Name=schooldbentities"))

The "Name=schooldbentities" here is the database connection string that gets the Schooldbentities node in the AppConfig

using (var con = new EntityConnection ("Name=schooldbentities"))
{
Con. Open ();
EntityCommand cmd = con. CreateCommand ();
Cmd.commandtext = "Select VALUE St from schooldbentities.students as St where St." Studentname= ' Nihao ' ";
Dictionary<int, string> dict = new Dictionary<int, string> ();
using (entitydatareader rdr = cmd. ExecuteReader (CommandBehavior.SequentialAccess | CommandBehavior.CloseConnection))
{
while (RDR. Read ())
{
int a = RDR. GetInt32 (0);
var B = rdr. GetString (1);
Dict. Add (A, b);
}
}
}

Rsql + raw sql ... "pour directly into SQL into DB"

People choose according to their hobbies ...

3. Rsql:

"1" repository in the Rsql query ....

Curd operation ...

1. R:var query = db. Students.sqlquery ("SELECT * from Student"). ToList ();

"2" at database level

1. R:var query = db. Database.sqlquery<student> ("SELECT * from Student"). ToList ();

2. c,u,d var query = db. Database.executesqlcommand ("Update Student set studentname= ' Jack2 ' where studentname= ' Jack '");

LINQ is too complex to write well ... Even with the linqer,linqpad ... LINQ <=> SQL

Learn about Entity Framework Other query methods Sql,raw SQL Analysis