C# ExecuteReader:尚未初始化连接属性。如何解决这个问题？

我有这个代码，我想从数据库中读取数据，然后比较它们。visualbasic说

“ExecuteReader:尚未初始化连接属性。”

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有什么帮助吗？

看起来您没有初始化属性。没有这一点，您的程序就无法知道如何使用

SqlConnection

执行

SqlCommand

。只需添加

int tempid,temp1,temp2,temp3,temp4,temp5,temp6;
{
    SqlCommand cmd = new SqlCommand("select * from Szelvenyek");
    SqlConnection cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=D:\Iskola\C#\lotto_kerekeshunor\lotto_kerekeshunor\Database1.mdf;Integrated Security=True;User Instance=True");
    cn.Open();
    SqlDataReader dr = cmd.ExecuteReader();
    while (dr.Read())
    {
        tempid = (int)dr["ID"];
        temp1 = (int)dr["elso"];
        temp2 = (int)dr["masodik"];
        temp3 = (int)dr["harmadik"];
        temp4 = (int)dr["negyedik"];
        temp5 = (int)dr["otodik"];
        temp6 = (int)dr["hatodik"];

        if (r1 == temp1 || r1 == temp2 || r1 == temp3 || r1 == temp4 || r1 == temp5 || r1 == temp6) talalat[tempid]++;
        if (r2 == temp1 || r2 == temp2 || r2 == temp3 || r2 == temp4 || r2 == temp5 || r2 == temp6) talalat[tempid]++;
        if (r3 == temp1 || r3 == temp2 || r3 == temp3 || r3 == temp4 || r3 == temp5 || r3 == temp6) talalat[tempid]++;
        if (r4 == temp1 || r4 == temp2 || r4 == temp3 || r4 == temp4 || r4 == temp5 || r4 == temp6) talalat[tempid]++;
        if (r5 == temp1 || r5 == temp2 || r5 == temp3 || r5 == temp4 || r5 == temp5 || r5 == temp6) talalat[tempid]++;
        if (r6 == temp1 || r6 == temp2 || r6 == temp3 || r6 == temp4 || r6 == temp5 || r6 == temp6) talalat[tempid]++;
    }
}

或者您可以将

SqlConnection

作为第二个参数传递给

SqlCommand

构造函数（我总是喜欢这样）

还可用于处理

SqlConnection

、

SqlCommand

和

SqlDataReader

等

SqlCommand cmd = new SqlCommand("select * from Szelvenyek", cn);

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这很容易忘记。您可以手动设置属性，也可以在连接后习惯性地构造命令，以便将其传递给构造函数：

using(SqlConnection cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=D:\Iskola\C#\lotto_kerekeshunor\lotto_kerekeshunor\Database1.mdf;Integrated Security=True;User Instance=True"))
using(SqlCommand cmd = new SqlCommand("select * from Szelvenyek", cn))
{
   cn.Open();
   using(SqlDataReader dr = cmd.ExecuteReader())
   {
      while(dr.Read())
      {
         ///
      }
   }
}

---

谢谢，我已经找了一个小时了！Visual Basic与此有什么关系？

using(SqlConnection cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=D:\Iskola\C#\lotto_kerekeshunor\lotto_kerekeshunor\Database1.mdf;Integrated Security=True;User Instance=True"))
using(SqlCommand cmd = new SqlCommand("select * from Szelvenyek", cn))
{
   cn.Open();
   using(SqlDataReader dr = cmd.ExecuteReader())
   {
      while(dr.Read())
      {
         ///
      }
   }
}

SqlConnection cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=D:\Iskola\C#\lotto_kerekeshunor\lotto_kerekeshunor\Database1.mdf;Integrated Security=True;User Instance=True");

SqlCommand cmd = new SqlCommand("select * from Szelvenyek", cn);