/// <summary>
/// 需要从外部关闭数据库连接（适用于多次连续数据库操作）
/// </summary>
/// <param name="name"></param>
/// <param name="helper">外部传入的DBHelper用以提供长数据库连接</param>
/// <returns></returns>
static public User GetUserByName(string name, DBHelper helper)
{
SqlParameter pName = new SqlParameter("@Name", name);
if (helper.HelperConnection.State == ConnectionState.Closed)
{
helper.HelperConnection.Open();
}
SqlDataReader reader = helper.ExecuteReader(@"SELECT * FROM [User] WHERE [Name]=@Name", pName);
if (reader.HasRows)
{
reader.Read();
}
else
{
return(new User()
{
Id = -1
}); //ID=-1表示没有该用户
}
User result = User.map(reader);
return(result);
}
///// <summary>
///// 根据用户名查找用户，返回用户ID(适用于单次数据库操作)
///// </summary>
///// <param name="name">用户名</param>
///// <returns></returns>
//static public int SeekUser(string name)
//{
// DBHelper dBHelper = new DBHelper();
// object result;
// using (dBHelper.HelperConnection)
// {
// dBHelper.HelperConnection.Open();
// result = dBHelper.ExecuteScalar($"SELECT [UserId] FROM [User] WHERE [UserName]='{name}'");
// }
// if (result == null)
// {
// return -1;
// }
// else
// {
// return (int)result;
// }
//}
/// <summary>
/// 根据用户名查找用户，返回用户ID,DBHelper的数据库连接需要在外界打开和关闭。（适用于连续数据库操作）
/// </summary>
/// <param name="name">用户名</param>
/// <param name="dBHelper">需要使用外界的DBHelper对象的数据库连接</param>
/// <returns></returns>
//static public int SeekUser(string name, DBHelper dBHelper)
//{
// object result;
// result = dBHelper.ExecuteScalar($"SELECT [Id] FROM [User] WHERE [Name]=N'{name}'");
// if (result == null)
// {
// return -1;
// }
// else
// {
// return (int)result;
// }
//}
static public IList <User> GetUsers()
{
IList <User> users = new List <User>();
DBHelper helper = new DBHelper();
helper.HelperConnection.Open();
SqlDataReader reader = helper.ExecuteReader("SELECT *FROM [User]");
//bool hasAnotherRow = reader.Read();
if (reader.HasRows)
{
while (reader.Read())
{
users.Add(User.map(reader));
}
}
helper.HelperConnection.Close();
return(users);
}
/// <summary>
/// 单次查询，由内部提供数据库连接对象
/// </summary>
/// <param name="Id"></param>
/// <returns></returns>
static public User GetUserById(int Id)
{
DBHelper helper = new DBHelper();
SqlParameter pId = new SqlParameter("@pId", Id);
helper.HelperConnection.Open();
SqlDataReader reader = helper.ExecuteReader(@"SELECT * FROM [User] WHERE [Id]=@pId", pId);
if (reader.HasRows)
{
reader.Read();
}
else
{
// return new User() { Id = -1 };//ID=-1表示没有该用户
return(null);
}
User result = User.map(reader);
helper.HelperConnection.Close();
return(result);
}
/// <summary>
/// 单次查询，由内部提供数据库连接对象
/// </summary>
/// <param name="name"></param>
/// <returns></returns>
static public User GetUserByName(string name)
{
DBHelper helper = new DBHelper();
SqlParameter pName = new SqlParameter("@Name", name);
helper.HelperConnection.Open();
SqlDataReader reader = helper.ExecuteReader(@"SELECT * FROM [User] WHERE [Name]=@Name", pName);
if (reader.HasRows)
{
reader.Read();
}
else
{
// return new User() { Id = -1 };//ID=-1表示没有该用户
return(null);
}
User result = User.map(reader);
helper.HelperConnection.Close();
return(result);
}