用c#编写winform的一个用户登录界面，实现功能点击登录进入主界面，包括数据库的链接

public static SqlConnection MyConnection()
{
return new SqlConnection("server=XXXXX;database=XXXXX;uid=XXXXX;pwd=XXXXX");
}

private void btnLogin_Click(object sender, EventArgs e)
{
………………
SqlConnection conn=MyConnection();

conn.Open();

SqlCommand cmd=new SqlCommand(SQL语句，匹配登录界面用户名密码和数据库用户名密码 ,conn);

SqlDataReader sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
sdr.Read();
if (sdr.HasRows)
{
//登陆成功

}
else
{
//用户名密码错误

}
sdr.Close();
}本回答被提问者和网友采纳

核心代码（本人没有SQLServer，所以用Access代替了，将所有的Ole替换成Sql就可以了，请参阅附件中的完整代码）：

namespace DALC
{
    using System.Configuration;
    using System.Data.OleDb;

    public class UserDal
    {
        public int GetUser(string userName, string password)
        {
            using (var connection = new OleDbConnection(ConfigurationManager.ConnectionStrings["LoginDemo.Properties.Settings.LoginDemoConnectionString"].ConnectionString))
            {
                var command = new OleDbCommand
                                       {
                                           Connection = connection,
                                           CommandText = @"SELECT COUNT(1) FROM Users 
                                                                                WHERE UserName = @UserName
                                                                                AND Password = @Password"
                                       };

                command.Parameters.AddWithValue("@UserName", userName);
                command.Parameters.AddWithValue("@Password", password);
                connection.Open();
                return (int)command.ExecuteScalar();
            }
        }
    }
}

using System.Data.SqlClient;

namespace Test1
{
    public partial class Form2 : Form
    {
        SqlConnection sqlconn = null;
        SqlCommand sqlcomm = null;
        string strconn = "";
        public Form2()
        {
            InitializeComponent();
        }

        private void Form2_Load(object sender, EventArgs e)
        {
            sqlconn = new SqlConnection();
            sqlcomm = new SqlCommand();
            strconn = "data source=(local);database=test;user id=sa;password=sa;Integrated Security=SSPI";//database中是你数据库名字，（local）表示连接本地数据库
            sqlconn.ConnectionString = strconn;
            sqlconn.Open();
            if (sqlconn.State == ConnectionState.Open)
                MessageBox.Show("连接成功");
            sqlcomm.Connection = sqlconn;
            sqlcomm.CommandType = CommandType.Text;
            sqlcomm.CommandText = "select * from ...";//这里就是数据库操作
            ...
            ...
            ...
        }
    }
}

我说楼主，你最好看一下书或者视频，到时候自己就能做了