c# - 如何从 sql server 2008 获取列值？

Question

我有一个有 5 列的表：

我写了这样的代码：

String SQLQuery = "SELECT count(*) FROM aspnet_Users where Username=@uname AND Password = @pwd";
    using(SqlConnection sqlConnection = new SqlConnection(strConnection))
    using(SqlCommand command = new SqlCommand(SQLQuery, sqlConnection))
    {
        sqlConnection.Open();
        command.Parameters.AddWithValue("@uname", Username);
        command.Parameters.AddWithValue("@pwd", Password);
        int result = Convert.ToInt32(command.ExecuteScalar());
        boolReturnValue = (result > 0);
    }

这里我需要一些额外的信息，如果上面的用户名和密码是正确的，我需要的是：用户 ID 和角色列数据

Answer 1

为什么你不这样做呢？

string SQLQuery = "SELECT UserId FROM aspnet_Users where Username=@uname AND Password = @pwd";
[...]
object result = command.ExecuteScalar();
if (result == null)
{
    boolReturnValue = false;
}
else
{
    long userId = Convert.ToInt64(result);
    boolReturnValue = true;
}

Answer 2

String SQLQuery = "SELECT Top 1 UserId, role  FROM aspnet_Users where Username=@uname AND Password = @pwd";
    using(SqlConnection sqlConnection = new SqlConnection(strConnection))
    using(SqlCommand command = new SqlCommand(SQLQuery, sqlConnection))
    {
        sqlConnection.Open();
        command.Parameters.AddWithValue("@uname", Username);
        command.Parameters.AddWithValue("@pwd", Password);

         SqlDataReader Reader = null;
         if (sqlConnection.State == ConnectionState.Closed || sqlConnection.State == ConnectionState.Broken)
                    sqlConnection.Open();
            Reader = command.ExecuteReader();
           if (Reader.Read())
          {
            int UserId = Convert.ToInt32(Reader["UserId"]);
            string Role = Convert.ToString(Reader["role"]);

          }

   }

Answer 3

试试这个代码

SELECT count(*),userid,role FROM aspnet_Users where Username=@uname AND Password = @pwd Group by userid,role 

Answer 4

为什么不直接获取 UserId 而不是 Count(*)，这样您的查询应该如下所示：

SELECT UserId FROM aspnet_Users where Username=@uname AND Password = @pwd

用户名应该是唯一的，因此您不应检索超过一行...如果您有多个相同的用户名和相同的密码，您可以添加前 1 个。