thanks martin...it seems with no query handling the database Next func does not run anyway as the rows evaluate to false in the for loop...
// tell other players in the room you have entered rows_users, err := database.Query("SELECT username FROM users WHERE room = ? AND username != ?", room, username) // if the user from the db is connected then send them a message var user string for rows_users.Next() { rows_users.Scan(&user) if conn, ok := m[user]; ok { conn.Write([]byte(string(username + " has entered the room\n# "))) } } I should probably print something in the loop to confirm but I certainly don't get any null pointer connection errors so may just comment this for clarity and leave it. I guess it saves more code ;-) On Saturday, September 12, 2020 at 9:53:28 PM UTC+1 mb0 wrote: > hi Andy, > > when you take a look at the documentation of the Rows type returned by > Query you will see a helpful example of its common use, appending the > scanned results into a slice. my recommendation would be to follow this > example and then check if the len(slice) == 0 to detect an empty set. > > if you don't actually need the results scanned into a go slice, consider > using query row with a sql select count(*) … query and scan, then check > the resulting integer. > > have fun! > > On 12.09.20 21:16, Andy Hall wrote: > > the database.Query func does not return ErrNoRows unlike the > > database.QueryRow func so how to I handle an empty set when I wish to > > run a query which returns multiple rows... > > > > // tell other players in the room you have entered > > rows_users, err := database.Query("SELECT username FROM users WHERE room > > = ? AND username != ?", room, username) > > // handle an empty set > > if err != nil { > > if err == sql.ErrNoRows { > > fmt.Println("EMPTY SET") > > } else { > > fmt.Println(err) > > return > > } > > > > The string "EMPTY SET" is never printed as the condition is never > > set...so continues to run through the if statement. > > > > Surely there is is way to handle no rows with Query ?? > > > > -- > > You received this message because you are subscribed to the Google > > Groups "golang-nuts" group. > > To unsubscribe from this group and stop receiving emails from it, send > > an email to golang-nuts...@googlegroups.com > > <mailto:golang-nuts...@googlegroups.com>. > > To view this discussion on the web visit > > > https://groups.google.com/d/msgid/golang-nuts/6d6c7d54-1a4b-4f07-bf22-8523045ce543n%40googlegroups.com > > > < > https://groups.google.com/d/msgid/golang-nuts/6d6c7d54-1a4b-4f07-bf22-8523045ce543n%40googlegroups.com?utm_medium=email&utm_source=footer > >. > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/0a03fd9c-b614-49ee-9d07-a7f44299fd7en%40googlegroups.com.