Come restituire il numero di righe trovate dalla query SELECT

Question

Come restituire il numero di righe trovate dalla query SELECT

16

83499 2014-01-29

Ho scritto unafunzione che dovrebbe restituireilnumero di righetrovatein una query SELECTma sembra sempre restituire 0 o un array. Ci sto scherzando da circa un'orae ancoranon riesco a capirlo! Sono sicuro che stofacendo qualcosa di stupidamente sbagliato.

Latabella MySQL

  + -------- + ------------- + -------------------- - +
|postid| ip| tempo|
+ -------- + ------------- + --------------------- +
| 1234| 192.168.0.1| 29/01/2014 14:27:02|
| 5678| 192.168.0.2| 29/01/2014 14:27:02|
+ -------- + ------------- + --------------------- +

PHP

  ### Cerca IPnel database
funzionepostviews_get_ip ($id,$ip) {
 global $post,$ wpdb;

    $ wpdb- >get_results ("SELEZIONA * DA $ wpdb- > wp_postviews_ips WHEREpostid=$id ANDip=$ip");

    $ rowcount=$ wpdb- >num_rows;

    return $ rowcount;
}

postviews_get_ip ($id,$ _SERVER ['REMOTE_ADDR']);
//sia $id che $ _SERVER ['REMOTE_ADDR']) restituisconoi valori che sto cercandonel database

I wrote a function which is supposed to return the number of rows found in a SELECT query but it always either seems to return 0 or an array. I have been messing around with this for about an hour now and I still can't figure it out! I'm sure I'm doing something stupidly wrong.

The MySQL Table

+--------+-------------+---------------------+
| postid |     ip      |        time         |
+--------+-------------+---------------------+
|   1234 | 192.168.0.1 | 2014-01-29 14:27:02 |
|   5678 | 192.168.0.2 | 2014-01-29 14:27:02 |
+--------+-------------+---------------------+

PHP

### Search for IP in database
function postviews_get_ip($id, $ip) {
    global $post, $wpdb;

    $wpdb->get_results("SELECT * FROM $wpdb->wp_postviews_ips WHERE postid = $id AND ip = $ip");

    $rowcount = $wpdb->num_rows;

    return $rowcount;
}

postviews_get_ip($id, $_SERVER['REMOTE_ADDR']);
//both $id and $_SERVER['REMOTE_ADDR']) return the values I'm searching for in the database

fonte
Swen

- Qual èilnome dellatabellae ilprefisso dellatabella?
  
  What is the name of the table and the table prefix?
  - 0
  - 2014-01-29
  - Chittaranjan
- @Chittaranjan Ilnome dellatabella è wp_postviews_ips,non sono sicuro di cosaintendiperprefisso dellatabella.
  
  @Chittaranjan Table name is wp_postviews_ips, I'm not sure what you mean by table prefix though.
  - 0
  - 2014-01-29
  - Swen
- Rimuovere "$ wpdb->" da $ wpdb-> wp_postviews_ips sembravafareiltrucco!
  
  Removing "$wpdb->" from $wpdb->wp_postviews_ips seemed to do the trick!
  - 0
  - 2014-01-29
  - Swen
- Questo èilmotivoper cui avevo chiestoilnomee ilprefisso dellatabella.Tutte letabelle di wordpress hanno unprefissoimpostato durante la configurazione del sito wordpress.Qui ci sonomaggiori dettagli su [codex] (http://codex.wordpress.org/Creating_Tables_with_Plugins#Database_Table_Prefix) Siprega di controllare lamia risposta aggiornata con l'uso corretto delnome dellatabella.
  
  That's the reason I had asked for the table name and prefix. All wordpress tables have a prefix which you set during setting up the wordpress site. Here are more details on [codex](http://codex.wordpress.org/Creating_Tables_with_Plugins#Database_Table_Prefix) Please check my updated answer with correct use of table name.
  - 0
  - 2014-01-29
  - Chittaranjan

2 risposta

voti

- 2
- 2014-01-29
Sembra che la query sia sbagliata.$ip è una stringa,quindi dovrestiinserire virgolette singoleintorno come sotto

$wpdb->get_results("SELECT * FROM {$wpdb->prefix}postviews_ips WHERE postid = $id AND ip = '$ip'");
Seems the query is wrong. $ip is string so you should put single quote around that as below

$wpdb->get_results("SELECT * FROM {$wpdb->prefix}postviews_ips WHERE postid = $id AND ip = '$ip'");
- Hoprovato questoe restituisce ancora 0.
  
  Tried this and it still returns 0.
  - 0
  - 2014-01-29
  - Swen

eteich · Accepted Answer · 2014-01-29

29

2014-01-29

Se stai semplicemente cercando di ottenere un conteggio,$wpdb->get_var();insieme all'utilizzo di COUNT()neltuo sql saràmigliore:

 ### Search for IP in database
function postviews_get_ip($id, $ip) {
    global $post, $wpdb;

    $rowcount = $wpdb->get_var("SELECT COUNT(*) FROM $wpdb->wp_postviews_ips WHERE postid = $id AND ip = '$ip'");

    return $rowcount;
}

postviews_get_ip($id, $_SERVER['REMOTE_ADDR']);
//both $id and $_SERVER['REMOTE_ADDR']) return the values I'm searching for in the database

Per quanto riguarda ciò che è andato stortoneltuoesempioprecedente,non stavi assegnando latuaistanza $wpdb->get_results() a una variabile,e senza diessa $wpdb->num_rows; restituirà zeropoichéin realtànonestrae dall'istanza della query,mapiuttosto dall'oggetto $ wbdbglobale.

Se desideri utilizzare get_results():

 ### Search for IP in database
function postviews_get_ip($id, $ip) {
    global $post, $wpdb;

    $ipquery= $wpdb->get_results("SELECT * FROM $wpdb->wp_postviews_ips WHERE postid = $id AND ip = '$ip'");
    $rowcount = $ipquery->num_rows;
    return $rowcount;
}

postviews_get_ip($id, $_SERVER['REMOTE_ADDR']);
//both $id and $_SERVER['REMOTE_ADDR']) return the values I'm searching for in the database

Manon vedrei lanecessità di questo ameno chetunon abbiabisogno dei risultati,nel qual caso restituirei l'oggetto $ipquerye userei num_rows su diesso quando Ne avevobisogno:

 ### Search for IP in database
function postviews_get_ip($id, $ip) {
    global $post, $wpdb;

    $ipquery = $wpdb->get_results("SELECT * FROM $wpdb->wp_postviews_ips WHERE postid = $id AND ip = '$ip'");
    return $ipquery;
}

$someVariable = postviews_get_ip($id, $_SERVER['REMOTE_ADDR']);
//both $id and $_SERVER['REMOTE_ADDR']) return the values I'm searching for in the database

echo $someVariable->num_rows;

If you are merely trying to get a count, $wpdb->get_var(); along with using COUNT() in your sql will be better:

### Search for IP in database
function postviews_get_ip($id, $ip) {
    global $post, $wpdb;

    $rowcount = $wpdb->get_var("SELECT COUNT(*) FROM $wpdb->wp_postviews_ips WHERE postid = $id AND ip = '$ip'");

    return $rowcount;
}

postviews_get_ip($id, $_SERVER['REMOTE_ADDR']);
//both $id and $_SERVER['REMOTE_ADDR']) return the values I'm searching for in the database

As to what went wrong in your previous example, you weren't assigning your $wpdb->get_results() instance to a variable, and without it $wpdb->num_rows; is just going to return zero as it isn't actually pulling from the instance of the query, but rather the global $wbdb object.

If you do want to use get_results():

### Search for IP in database
function postviews_get_ip($id, $ip) {
    global $post, $wpdb;

    $ipquery= $wpdb->get_results("SELECT * FROM $wpdb->wp_postviews_ips WHERE postid = $id AND ip = '$ip'");
    $rowcount = $ipquery->num_rows;
    return $rowcount;
}

postviews_get_ip($id, $_SERVER['REMOTE_ADDR']);
//both $id and $_SERVER['REMOTE_ADDR']) return the values I'm searching for in the database

But I wouldn't see the need for that unless you needed the results, in which case I would just return the $ipquery object and use num_rows on it when I needed it:

### Search for IP in database
function postviews_get_ip($id, $ip) {
    global $post, $wpdb;

    $ipquery = $wpdb->get_results("SELECT * FROM $wpdb->wp_postviews_ips WHERE postid = $id AND ip = '$ip'");
    return $ipquery;
}

$someVariable = postviews_get_ip($id, $_SERVER['REMOTE_ADDR']);
//both $id and $_SERVER['REMOTE_ADDR']) return the values I'm searching for in the database

echo $someVariable->num_rows;

fonte
eteich

Piccola aggiunta.Dovresti sempre usareprepare (https://developer.wordpress.org/reference/classes/wpdb/prepare/) quandoesegui qualsiasi queryperprevenire l'iniezione sql.

Small addition. You should always use prepare (https://developer.wordpress.org/reference/classes/wpdb/prepare/) when executing any queries to prevent sql injection.
- 1
- 2019-05-29
- Maciej Paprocki
In realtànon dovrebbeessere unapiccola aggiunta,èmoltoimportantenon rendereiltuo codice sfruttabiletramite sqlinjection.

Actually that shouldnt be a small addition, that's very important not to make your code exploitable via sql injection.
- 0
- 2019-09-12
- Max Carroll