Returning a single row

Question

I\'m trying to return a single row from a database:

using (connection = new SqlConnection(ConfigurationManager.AppSettings[\"connection\"]))
{
    using (command         


        

Answer 1

reader["col_1"] returns object.

You want something like reader.GetString(reader.GetOrdinal("col_1")).

Edit -> I just wanted to add a note here that, in addition to the concerns others have raised, a SELECT TOP without an ORDER BY can give you random results based on schema changes and/or merry-go-round scans.

Answer 2

To me it seems, you don't want a single row, only a single value:

SqlConnection sqlConnection = new SqlConnection("Your Connection String");
SqlCommand cmd = new SqlCommand();
Object returnValue;

cmd.CommandText = "SELECT TOP 1 col_name FROM Customers";
cmd.CommandType = CommandType.Text;
cmd.Connection = sqlConnection1;

sqlConnection.Open();

returnValue = cmd.ExecuteScalar();

sqlConnection.Close();

return returnValue.ToString(); //Note you have to cast it to your desired data type

Answer 3

You can use an if statement if your query only returns one value

[...]
string x = string.Empty;
if(reader.Read()) {
    // make sure the value is not DBNull
    if(DBNull.Value != reader["col_1"]) {
       x = reader.GetString(0);
    }
}
[...]

Answer 4

The problem is the return type. The method you are in is expecting you to return a string, but reader["col_1"] is an object. I suggest returning reader["col_1"].ToString() or Convert.ToString(reader["col_1"]).

Answer 5

the reader returns object which you should cast it to what you need, in this case a string.

you can use any of this codes :

return reader.GetString(0);

return reader["col_1"].ToString();

return Convert.ToString(reader["col_1"]);

return reader["col_1"] as string;

but dont forget to close the connection and reader before leaving the function.

string ret = reader.GetString(0);
reader.Close();
connection.Close();
return ret;

Answer 6

Follow the following steps to select a single colume, and display them.

    //create a connection
    SqlConnection sqlConnection = new SqlConnection("Your Connection String");
    SqlCommand cmd = new SqlCommand();
    cmd.Connection = sqlConnection;

    //open the connection
    sqlConnection.Open();

    //Your command query string
    cmd.CommandType = CommandType.Text;
    cmd.CommandText = "SELECT TOP 1 col_name FROM Customers";


    //Execute the reader
    SqlDataReader result  = cmd.ExecuteReader();
    result.Read();

    //close the connection
    sqlConnection.Close();

    return result["coiumn_name"].ToString();