Invalid attempt to read when no data is present

Question

private void button1 Click object sender  EventArgs e                string name          name   textBox5 Text          SqlConnection con10   new SqlConnection  quot con strn quot            SqlCommand cmd10   new SqlCommand  quot select   from sumant where username  name quot            cmd10 Parameters AddWithValue  quot  name quot  name           cmd10 Connection   con10          cmd10 Connection Open     line 7         SqlDataReader dr   cmd10 ExecuteReader               if   textBox2 Text    dr 2  ToString                    do something         When I debug until line 7  it is OK  but after that dr throws an exception   Invalid attempt to read when no data is present   I don t understand why I m getting that exception  since I do have data in the table with username sumant  Please tell me whether the  if  statement is correct or not  And how do I fix the error

User · Answer

I was having 2 values which could contain null values.

while(dr.Read())
 {
    Id = dr["Id"] as int? ?? default(int?);
    Alt =  dr["Alt"].ToString() as string ?? default(string);
    Name = dr["Name"].ToString()
 }

resolved the issue

User · Answer

I would check to see if the SqlDataReader has rows returned first   SqlDataReader dr   cmd10 ExecuteReader    if  dr HasRows

User · Answer

I just had this error  I was calling dr NextResult   instead of dr Read

User · Answer

You have to call DataReader Read to fetch the result   SqlDataReader dr   cmd10 ExecuteReader    if  dr Read              read data for first record here     DataReader Read   returns a bool indicating if there are more blocks of data to read  so if you have more than 1 result  you can do   while  dr Read              read data for each record here

User · Answer

I used the code below and it worked for me    String email         SqlDataReader reader cmd ExecuteReader        if reader Read             email reader  Email   ToString           String To email

User · Answer

You have to call dr Read   before attempting to read any data  That method will return false if there is nothing to read

[c#] Invalid attempt to read when no data is present

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