How to use executeReader() method to retrieve the value of just one cell

Question

I need to execute the following command and pass the result to a label. I don't know how can i do it using Reader. Someone can give me a hand?

String sql = "SELECT * FROM learer WHERE learer.id = " + index; SqlCommand cmd = new SqlCommand(sql,conn); learerLabel.Text = (String) cmd.ExecuteReader(); 

As you can see i create the SQL statement and i execute it, but it does not work. Why?

The console says:

Cannot implicitly SqlDataReader to String...

How can i get the desired results as String so the label can display it properly.

Answer 1

It is not recommended to use DataReader and Command.ExecuteReader to get just one value from the database. Instead, you should use Command.ExecuteScalar as following:

String sql = "SELECT ColumnNumber FROM learer WHERE learer.id = " + index; SqlCommand cmd = new SqlCommand(sql,conn); learerLabel.Text = (String) cmd.ExecuteScalar(); 

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Here is more information about Connecting to database and managing data.

Answer 2

using (var conn = new SqlConnection(SomeConnectionString)) using (var cmd = conn.CreateCommand()) {     conn.Open();     cmd.CommandText = "SELECT * FROM learer WHERE id = @id";     cmd.Parameters.AddWithValue("@id", index);     using (var reader = cmd.ExecuteReader())     {         if (reader.Read())         {             learerLabel.Text = reader.GetString(reader.GetOrdinal("somecolumn"))         }     } }