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Entity Framework系列之Code First

2024-11-04 10:48:39   208人阅读

第一步：安装Entity Framework6.0

使用管理NuGet程序包界面安装EntityFramework

第二步：新建实体类

using System.ComponentModel.DataAnnotations;namespace EFDemo4{    public class User    {        [Key]        public int Id { get; set; }        public string Name { get; set; }    }}

第三步：新建实体上下文类

using System.Data.Entity;namespace EFDemo4{    public class TestDBContext: DbContext    {        public TestDBContext()            : base("name=TestDB3")        {        }        public DbSet<User> Users { get; set; }    }}

App.config文件中的数据库连接字符串 
<connectionStrings>    <add name="TestDB3" providerName="System.Data.SqlClient" connectionString="Data Source=.\CMDB;Initial Catalog=TestDB3;Integrated Security=SSPI;" />  </connectionStrings>

第四步：增删改查

在执行数据库操作之后，数据库对象会自动创建

using System;using System.Data.Entity;using System.Linq;using System.Windows.Forms;namespace EFDemo4{    public partial class Form1 : Form    {        TestDBContext entity = new TestDBContext();        public Form1()        {            InitializeComponent();        }        /// <summary>        /// 新增        /// </summary>        private void Add()        {            User model = new User()            {                Name = DateTime.Now.ToString("yyyy-MM-dd hh:mm:ss")            };            entity.Users.Add(model);            entity.SaveChanges();            Query();        }        /// <summary>        /// 删除        /// </summary>        private void Delete()        {            if (listBox1.SelectedItem == null)            {                return;            }            int id = Convert.ToInt32(listBox1.SelectedItem.ToString().Split(‘-‘)[0]);            User model = entity.Users.Where(a => a.Id == id).FirstOrDefault();            if (model != null)            {                entity.Entry(model).State = EntityState.Deleted;                entity.SaveChanges();                Query();            }        }        /// <summary>        /// 修改        /// </summary>        private void Edit()        {            if (listBox1.SelectedItem == null)            {                return;            }            int id = Convert.ToInt32(listBox1.SelectedItem.ToString().Split(‘-‘)[0]);            User model = entity.Users.Where(a => a.Id == id).FirstOrDefault();            if (model != null)            {                model.Name = DateTime.Now.ToString("yyyy-MM-dd hh:mm:ss");                entity.Entry(model).State = EntityState.Modified;                entity.SaveChanges();                Query();            }        }        /// <summary>        /// 查询        /// </summary>        private void Query()        {            listBox1.Items.Clear();            var expr = from p in entity.Users select p;            foreach (var item in expr)            {                listBox1.Items.Add(string.Format("{0}-{1}", item.Id, item.Name));            }        }        private void toolStripButton1_Click(object sender, EventArgs e)        {            Add();        }        private void toolStripButton4_Click(object sender, EventArgs e)        {            Edit();        }        private void toolStripButton3_Click(object sender, EventArgs e)        {            Delete();        }        private void toolStripButton2_Click(object sender, EventArgs e)        {            Query();        }    }}

Entity Framework系列之Code First


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