Linq to SQL的增删改查

1. 新建一个工程

2. 创建数据库，添加表，然后在VS中的Server Explorer中连接到数据库。

3. 在工程中添加LINQ to SQL Classes，随便命名。然后将刚才的数据表拖进来。保存，OK。

以下是示例代码：

namespace LinqToSQLWinform
{
    public partial class Form1 : Form
    {
        DBDataContext db = new DBDataContext();
        public Form1()
        {
            InitializeComponent();
        }

        /// <summary>
        /// Add user
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnAdd_Click(object sender, EventArgs e)
        {
            var uu = db.Users.SingleOrDefault<User>(u => u.ID == txtID.Text);
            if (uu != null)
            {
                User user = new User
                {
                    ID = txtID.Text,
                    Name = txtName.Text,
                    Age = txtAge.Text,
                    Address = txtAddr.Text
                };
                db.Users.InsertOnSubmit(user);
                db.SubmitChanges();
                MessageBox.Show("Add user successed");
                txtID.Text = txtName.Text = txtAge.Text = txtAddr.Text = "";
            }
            else
                MessageBox.Show("This user is exist");

        }

        /// <summary>
        /// Query user
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnQuery_Click(object sender, EventArgs e)
        {
            var u = from uu in db.Users
                    where uu.ID == txtID.Text
                    select uu;
            if (u.Count() > 0)
            {
                User user = u.FirstOrDefault();
                txtName.Text = user.Name;
                txtAge.Text = user.Age;
                txtAddr.Text = user.Address;
            }
        }

        /// <summary>
        /// Update user
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnUpdate_Click(object sender, EventArgs e)
        {
            var user = db.Users.SingleOrDefault<User>(u => u.ID == txtID.Text);
            if (user != null)
            {
                user.Name = txtName.Text;
                user.Age = txtAge.Text;
                user.Address = txtAddr.Text;
                db.SubmitChanges();
                MessageBox.Show("Update user successed");
            }
            else
                MessageBox.Show("This user is exist");
        }

        /// <summary>
        /// Delete user
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnDelete_Click(object sender, EventArgs e)
        {
            var user = db.Users.SingleOrDefault<User>(u => u.ID == txtID.Text);
            if (user != null)
            {
                db.Users.DeleteOnSubmit(user);
                db.SubmitChanges();
                MessageBox.Show("Delete user successed");
            }
            else
                MessageBox.Show("This user is exist");
        }
    }
}