C#增删改查代码

//增加
DataBase dataBase = new DataBase();
                SqlConnection sqlConnection = dataBase.getConn();

                //打开连接
                sqlConnection.Open();


                //定义sql语句
                string sql = "insert into test1007.guest.person values('"+personIdText.Text+"','"+personNameText.Text+"','"+personPasswordText.Text+"','"+personRoleText.SelectedItem.ToString()+"')";

                //执行sqlCommand对象
                SqlCommand sqlCommand = new SqlCommand(sql, sqlConnection);

                sqlCommand.ExecuteNonQuery();
                MessageBox.Show("员工信息保存成功！");
                
                //关闭连接
                sqlConnection.Close();

//修改
DataBase dataBase = new DataBase();
            SqlConnection sqlConnection = dataBase.getConn();

            //打开连接
            sqlConnection.Open();


            //定义sql语句
            string sql = "update test1007.guest.person set name='"+personNameText.Text+"',password='"+personPasswordText.Text+"',role='"+personRoleText.SelectedItem.ToString()+"' where id='"+personIdText.Text+"'";

            //执行sqlCommand对象
            SqlCommand sqlCommand = new SqlCommand(sql, sqlConnection);

            sqlCommand.ExecuteNonQuery();
            MessageBox.Show("员工信息修改成功！");

            //关闭连接
            sqlConnection.Close();

//查询
DataBase dataBase = new DataBase();
            SqlConnection sqlConnection = dataBase.getConn();

            //打开连接
            sqlConnection.Open();


            //定义sql语句
            string sql = "select * from test1007.guest.person where role = '"+checkPerson.Text+"'";

            //执行sqlCommand对象
            SqlCommand sqlCommand = new SqlCommand(sql, sqlConnection);

            //创建数据适配器
            SqlDataAdapter sqlDataAdapter = new SqlDataAdapter();

            //执行sql语句
            sqlDataAdapter.SelectCommand = sqlCommand;

            //创建数据集
            DataSet dataSet = new DataSet();

            sqlDataAdapter.Fill(dataSet, "test1007.guest.person");

            personData.DataSource = dataSet.Tables[0];

            //关闭连接
            sqlConnection.Close();

//删除
DataBase dataBase = new DataBase();
                SqlConnection sqlConnection = dataBase.getConn();

                //打开连接
                sqlConnection.Open();


                //定义sql语句
                string sql = "delete from test1007.guest.person where id = '"+key+"'";

                //执行sqlCommand对象
                SqlCommand sqlCommand = new SqlCommand(sql, sqlConnection);

                sqlCommand.ExecuteNonQuery();
                MessageBox.Show("员工信息删除成功！");

                //关闭连接
                sqlConnection.Close();