public class DBHelper
{
//连接数据库
static SqlConnection conn = new SqlConnection("Data Source=DESKTOP-H22HG80\\SQL2014;Initial Catalog=Unity6;Integrated Security=True");
static SqlDataReader sdr;
/// <summary>
/// 获取数据流 查询、显示、绑定下拉
/// </summary>
/// <param name="sql"></param>
/// <returns></returns>
private static SqlDataReader GetDataReader(string sql)
{
try
{
//打开
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}
//命令对象
SqlCommand cmd = new SqlCommand(sql, conn);
sdr = cmd.ExecuteReader();
return sdr;
}
catch (Exception)
{
if (sdr != null && !sdr.IsClosed)//数据流关闭
{
sdr.Close();
}
throw;
}

}
/// <summary>
/// 返回受影响行数
/// 添加、删除、修改
/// </summary>
/// <param name="sql"></param>
/// <returns></returns>
public static int ExecuteNonQuery(string sql)
{
try
{
//打开
//判断状态
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}

//命令对象
SqlCommand cmd = new SqlCommand(sql, conn);
int n = cmd.ExecuteNonQuery();
if (conn.State == ConnectionState.Open)
{
conn.Close();
}
return n;
}
catch (Exception)
{
throw;
}
}
/// <summary>
/// 数据流转List
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="sdr"></param>
/// <returns></returns>
private static List<T> DataReaderToList<T>(SqlDataReader sdr)
{
Type t = typeof(T);//获取类型
//获取所有属性
PropertyInfo[] p = t.GetProperties();
//定义集合
List<T> list = new List<T>();
//遍历数据流
while (sdr.Read())
{
//创建对象
T obj = (T)Activator.CreateInstance(t);
//数据流列数
string[] sdrFileName = new string[sdr.FieldCount];
for (int i = 0; i < sdr.FieldCount; i++)
{
sdrFileName[i] = sdr.GetName(i).Trim();
}
foreach (PropertyInfo item in p)
{
//判断Model中的属性是否在流的列名中
if (sdrFileName.ToList().IndexOf(item.Name) > -1)
{
if (sdr[item.Name] != null)
{
item.SetValue(obj, sdr[item.Name]);//对象属性赋值
}
else
{
item.SetValue(obj, null);//对象属性赋值
}
}
else
{
item.SetValue(obj, null);//对象属性赋值
}

}
list.Add(obj);
}
return list;
}
/// <summary>
/// 获取list集合
/// </summary>
/// <typeparam name="T"></typeparam>
/// <returns></returns>
public static List<T> GetToList<T>(string sql)
{
//获取流数据
SqlDataReader sdr = GetDataReader(sql);
List<T> list = DataReaderToList<T>(sdr);
if (!sdr.IsClosed)//数据流关闭
{
sdr.Close();
}
return list;
}
/// <summary>
/// 返回首行首列
/// </summary>
/// <param name="sql"></param>
/// <returns></returns>
public static object ExecuteScalar(string sql)
{
try
{
//打开
//判断状态
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}

//命令对象
SqlCommand cmd = new SqlCommand(sql, conn);
object n = cmd.ExecuteScalar();
if (conn.State == ConnectionState.Open)
{
conn.Close();
}
return n;
}
//获取所要进行修改的行的主键 request获取页所传来的值
//t.qdid = Convert.ToInt32(Request["qdid"]);
catch (Exception)
{
throw;
}
}