Question

The below code is the web method (is the most common one as you can see it everywhere), but i keep getting the error from the title. I am at the beginning with .NET, so if anyone can point me into the right direction , please do so.

SqlConnection myConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["mySQLconn"].ConnectionString);

[WebMethod(Description = "Select Customers")]
    public string GetVersionofSelectedCustomer(string versionEmail)
    {

        string select = "SELECT version FROM customer WHERE EMAIL = '" + versionEmail + "'";
        SqlDataAdapter adapter = new SqlDataAdapter(select, myConnection);

        DataSet custDS = new DataSet();            
        //adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey;
        adapter.Fill(custDS, "Customers");

        return custDS;

    }

connection is defined in the Web.config (local connection) and return custDS; is where it fails.

Answer 1

The return type of your function is string and you are trying to return a DataSet object. You can try like this:

public DataSet GetVersionofSelectedCustomer(string versionEmail)
{
     string select = "SELECT version FROM customer WHERE EMAIL = '" + versionEmail + "'";
     SqlDataAdapter adapter = new SqlDataAdapter(select, myConnection);

     DataSet custDS = new DataSet();            
     //adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey;
     adapter.Fill(custDS, "Customers");

     return custDS;

}