EF简单查询

时间:2023-03-09 16:10:21
EF简单查询
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.Objects;
using System.Data.EntityClient;
using System.Collections; namespace EFDemo
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
} private void button1_Click(object sender, EventArgs e)
{
ArrayList lst = new ArrayList();
using (NhibernateDBEntities ndb = new NhibernateDBEntities())
{
Teacher teachs = ndb.Teacher.Where(it=>it.Name=="Anby");
ndb.DeleteObject(teachs);
ndb.SaveChanges(); Teacher teach2 = ndb.Teacher.Where(it => it.Name == "Anby");
}
} private static void Updateo()
{
ArrayList lst = new ArrayList();
using (NhibernateDBEntities ndb = new NhibernateDBEntities())
{
Teacher teachs = ndb.Teacher.FirstOrDefault();
teachs.Age = ;
ndb.SaveChanges(); Teacher teach2 = ndb.Teacher.FirstOrDefault();
}
} private static void Add()
{
ArrayList lst = new ArrayList();
Teacher teacher = new Teacher()
{
Name = "Anby",
Age = ,
School_ID = ,
Sex = "男"
};
using (NhibernateDBEntities ndb = new NhibernateDBEntities())
{
ndb.AddToTeacher(teacher);
ndb.SaveChanges();
ObjectResult<Teacher> teachs = ndb.CreateQuery<Teacher>("Select VALUE c from NhibernateDBEntities.Teacher as c").Execute(MergeOption.NoTracking); foreach (Teacher item in teachs)
{
lst.Add(item); } } } private static void ParamEsql(ArrayList lst, NhibernateDBEntities ndb)
{
//带参数的查询
string strsql = "Select VALUE c from NhibernateDBEntities.School as c " +
" where c.id=@schoolid";
ObjectQuery<School> query = ndb.CreateQuery<School>(strsql);
//增加查询参数
query.Parameters.Add(new ObjectParameter("schoolid", ));
ObjectResult<School> result = query.Execute(MergeOption.NoTracking);
foreach (School c in result)
lst.Add(c);
} private void BaseQuery()
{
List<string> lst = new List<string>();
using (NhibernateDBEntities ndb = new NhibernateDBEntities())
{
//查询所有
foreach (var teacher in ndb.Teacher)
{
lst.Add(teacher.Name);
}
comboBox1.DataSource = lst; //单个数据查询
Teacher tea1 = ndb.Teacher.Where("it.Name='Jessica'").First(); Teacher tea2 = ndb.Teacher.First<Teacher>(it => it.Name == "Jessica"); Teacher tea3 = (from c in ndb.Teacher
where c.Name == "Jessica"
select c).First(); //多表连接查询
School sch = ndb.School.First<School>(s => s.id == ); foreach (Teacher item in sch.Teacher)
{
lst.Add(item.Name);
} }
}
} }