namespace 用户登录第一版
{
    public partial class Manager : Form
    {
        public Manager()
        {
            InitializeComponent();
        }
        //用户编号用户名姓名身份证号电话地址年龄性别
        private void btnlook_Click(object sender, EventArgs e)
        {
            GetDatatable();
        }

        private void GetDatatable()
        {
            string strcon = ConfigurationManager.ConnectionStrings["sqlserver2008"].ConnectionString;
            SqlConnection sqlcnn = new SqlConnection(strcon);
            SqlCommand sqlcmm = sqlcnn.CreateCommand();
            sqlcnn.Open();
            string sqlstr = "select U.UserId,U.UserName,isnull(U.Error,0)Error,UI.Name,isnull(UI.Sfzh,'还未填写')Sfzh ,UI.Tell,UI.Address,UI.Age,(case UI.General when 1 then '男' when 1 then '女' end) General from T_User U left outer join T_UserInfo UI on U.UserId=UI.UserId where ";
            string sqlwhere = returnsqlwhere(sqlcmm);
            sqlcmm.CommandText = sqlstr + sqlwhere;
            DataTable dt = new DataTable();
            SqlDataAdapter adapter = new SqlDataAdapter(sqlcmm);
            adapter.Fill(dt);
            if (dt.Rows.Count > 0)
            {
                this.dataGridView1.DataSource = dt;
            }
            else
            {
                MessageBox.Show("对不起，没有您所查找的数据");
            }
        }

        //返回动态生成的where子句
        private string returnsqlwhere(SqlCommand sqlcmm)
        {
            string sqlwhere = string.Empty;
            switch (cmbselect.Text)
            {
                case "姓名":
                    sqlwhere = "UI.Name like @name";
                    sqlcmm.Parameters.AddWithValue("@name", "%" + txtcontent.Text + "%");
                    break;
                case "年龄":
                    sqlcmm.Parameters.AddWithValue("@age", "%" + txtcontent.Text + "%");
                    sqlwhere = "UI.Age like @age";
                    break;
                case "地址":
                    sqlcmm.Parameters.AddWithValue("@address", "%" + txtcontent.Text + "%");
                    sqlwhere = "UI.Address like @address";
                    break;
                case "电话":
                    sqlcmm.Parameters.AddWithValue("@tell", "%" + txtcontent.Text + "%");
                    sqlwhere = "UI.Tell like @tell";
                    break;
                default:
                    sqlcmm.Parameters.AddWithValue("@sfzh", "%" + txtcontent.Text + "%");
                    sqlwhere = "UI.Sfzh like @sfzh";
                    break;
            }
            return sqlwhere;
        }

        private void btnadd_Click(object sender, EventArgs e)
        {
            UserAdd U = new UserAdd();
            //U.MdiParent = this;
            U.Show();
        }

        private void btnunlock_Click(object sender, EventArgs e)
        {
            string strcon = ConfigurationManager.ConnectionStrings["sqlserver2008"].ConnectionString;
            SqlConnection sqlcnn = new SqlConnection(strcon);
            SqlCommand sqlcmm = sqlcnn.CreateCommand();
            sqlcnn.Open();
            int id = Convert.ToInt32(this.dataGridView1.SelectedCells[0].Value);
            sqlcmm.CommandText = "update T_User set Error=0 where UserId=@userid";
            sqlcmm.Parameters.AddWithValue("@userid",id);
            if (sqlcmm.ExecuteNonQuery()>0)
            {
                MessageBox.Show("解锁成功！");
            }
            else
            {
                MessageBox.Show("解锁失败！");
            }
        }//解锁

        private void btnrefresh_Click(object sender, EventArgs e)
        {
            GetDatatable();
        }//刷新
        private void btnGUID_Click(object sender, EventArgs e)
        {
            Guid g = Guid.NewGuid();
            MessageBox.Show(g.ToString());
        }//获取一个GUID值

        private void btndelete_Click(object sender, EventArgs e)
        {
            string strcon = ConfigurationManager.ConnectionStrings["sqlserver2008"].ConnectionString;
            SqlConnection sqlcnn = new SqlConnection(strcon);
            SqlCommand sqlcmm = sqlcnn.CreateCommand();
            sqlcnn.Open();
            //int id = Convert.ToInt32(this.dataGridView1.SelectedCells[0].Value);
            int rowid = 0;
            rowid = Convert.ToInt32(dataGridView1.CurrentRow.Cells[0].Value.ToString().Trim());
            if (dataGridView1.CurrentRow!=null&&dataGridView1.SelectedRows.Count!=0)
            {
                MessageBox.Show("是否删除，删除后不可恢复","警告",MessageBoxButtons.YesNo);
                sqlcmm.CommandText = "delete from T_User where UserId=@userid";
                sqlcmm.CommandText = "delete from T_UserInfo where UserId=@userid";
                sqlcmm.Parameters.AddWithValue("@userid",rowid);
                int a = sqlcmm.ExecuteNonQuery();
                GetDatatable();
                if (a<1)
                {
                    MessageBox.Show("删除失败！");
                }
            }
            else
            {
                MessageBox.Show("一次只能选择一行，不能选择单元格！");
            }

        }//删除
    }
}

增加用户信息：

namespace 用户登录第一版
{
    public partial class UserAdd : Form
    {
        public UserAdd()
        {
            InitializeComponent();
        }

        private void btnsave_Click(object sender, EventArgs e)
        {
            string strcon = ConfigurationManager.ConnectionStrings["sqlserver2008"].ConnectionString;
            SqlConnection sqlcnn = new SqlConnection(strcon);
            SqlCommand sqlcmm = sqlcnn.CreateCommand();
            sqlcnn.Open();
            sqlcmm.CommandText = "insert into T_User(UserName,Password) values(@username,@password) select @@identity";
            sqlcmm.Parameters.AddWithValue("@username",TxtUserName.Text);
            sqlcmm.Parameters.AddWithValue("@password",TxtPassword.Text);
            int result = Convert.ToInt32(sqlcmm.ExecuteScalar());
            MessageBox.Show(result.ToString());
            if (result>0)
            {
                int general = 0;
                switch (txtgeneral.Text)
                {
                    case "男":
                        general = 1;
                        break;
                    default:
                        general = 0;
                        break;
                }
                sqlcmm.CommandText = "insert into T_UserInfo (UserId,Name,sfzh,Tell,Address,Age,General) values(@userid,@name,@sfzh,@tell,@address,@age,@general)";
                sqlcmm.Parameters.AddWithValue("@userid",result);
                sqlcmm.Parameters.AddWithValue("@name",txtname.Text);
                sqlcmm.Parameters.AddWithValue("@sfzh", txtsfzh.Text);
                sqlcmm.Parameters.AddWithValue("@tell",txttell.Text);
                sqlcmm.Parameters.AddWithValue("@address",txtaddress.Text);
                sqlcmm.Parameters.AddWithValue("@age",txtage.Text);
                sqlcmm.Parameters.AddWithValue("@general",general);
                int result1 = sqlcmm.ExecuteNonQuery();
                if (result1>0)
                {
                    MessageBox.Show("插入成功！");
                }
                else
                {
                    MessageBox.Show("插入失败！");
                }
            }
            else
            {
                MessageBox.Show("数据没有插入成功！");
            }
        }

        private void btncancel_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}