mysql_affected_rows

(PHP 4, PHP 5)

mysql_affected_rows — Get number of affected rows in previous MySQL operation

Avviso

Questa enstensione deprecata da PHP 5.5.0, e sarà rimossa in futuro. Al suo posto, usare l'estensione MySQLi o PDO_MySQL. Vedere anche la guida MySQL: scelta dell'API e le FAQ relative per ulteriori informazioni. Le alternative a questa funzione includono:

Descrizione

mysql_affected_rows(resource $link_identifier = NULL): int

Get the number of affected rows by the last INSERT, UPDATE, REPLACE or DELETE query associated with link_identifier.

Elenco dei parametri

link_identifier: La connessione MySQL. Se l'identificativo di connessione non è specificato, l'ultima connessione aperta da mysql_connect() viene assunta. Se questa connessione non è trovata, si cercherà di crearne una come se mysql_connect() fosse stata chiamata senza argomenti. Se una connessione non è trovata oppure non viene stabilita, un avviso di livello E_WARNING viene generato.

Valori restituiti

Returns the number of affected rows on success, and -1 if the last query failed.

If the last query was a DELETE query with no WHERE clause, all of the records will have been deleted from the table but this function will return zero with MySQL versions prior to 4.1.2.

When using UPDATE, MySQL will not update columns where the new value is the same as the old value. This creates the possibility that mysql_affected_rows() may not actually equal the number of rows matched, only the number of rows that were literally affected by the query.

The REPLACE statement first deletes the record with the same primary key and then inserts the new record. This function returns the number of deleted records plus the number of inserted records.

In the case of "INSERT ... ON DUPLICATE KEY UPDATE" queries, the return value will be 1 if an insert was performed, or 2 for an update of an existing row.

Esempi

Example #1 mysql_affected_rows() example

<?php
$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
mysql_select_db('mydb');

/* this should return the correct numbers of deleted records */
mysql_query('DELETE FROM mytable WHERE id < 10');
printf("Records deleted: %d\n", mysql_affected_rows());

/* with a where clause that is never true, it should return 0 */
mysql_query('DELETE FROM mytable WHERE 0');
printf("Records deleted: %d\n", mysql_affected_rows());
?>

Il precedente esempio visualizzerà qualcosa simile a:

Records deleted: 10
Records deleted: 0

Example #2 mysql_affected_rows() example using transactions

<?php
$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
mysql_select_db('mydb');

/* Update records */
mysql_query("UPDATE mytable SET used=1 WHERE id < 10");
printf ("Updated records: %d\n", mysql_affected_rows());
mysql_query("COMMIT");
?>

Il precedente esempio visualizzerà qualcosa simile a:

Updated Records: 10

Note

Nota: Transactions

If you are using transactions, you need to call mysql_affected_rows() after your INSERT, UPDATE, or DELETE query, not after the COMMIT.

Nota: SELECT Statements

To retrieve the number of rows returned by a SELECT, it is possible to use mysql_num_rows().

Nota: Cascaded Foreign Keys

mysql_affected_rows() does not count rows affected implicitly through the use of ON DELETE CASCADE and/or ON UPDATE CASCADE in foreign key constraints.

Vedere anche:

mysql_num_rows() - Get number of rows in result
mysql_info() - Get information about the most recent query

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User Contributed Notes 11 notes

down

Ome Ko ¶

13 years ago


There are no rows affected by an update with identical data.
So here is one very ugly solution for these cases:
<?
function mysql_matched_rows() {
   $_kaBoom=explode(' ',mysql_info());
   return $_kaBoom[2];
}
?>

down

temp02 at flexis dot com dot br ¶

19 years ago


SCENARIO
1. You're using MySQL 4.1x with foreign keys.
2. You have table t2 linked to table t1 by a CASCADE ON DELETE foreign key.
3. t2 has a UNIQUE key so that duplicate records are unacceptable.
3. You have a REPLACE query on t1 followed by an INSERT query on t2 and expect the second query to fail if there's an attempted insert of a duplicate record.

PROBLEM
You notice that the second query is not failing as you had expected even though the record being inserted is an exact duplicate of a record previously inserted.

CAUSE
When the first query (the REPLACE query) deletes a record from t1 in the first stage of the REPLACE operation, it cascades the delete to the record that would be duplicated in t2. The second query then does not fail because the "duplicate" record is no longer a duplicate, as the original one has just been deleted.

down

ahmd ¶

8 years ago


I was just testing  "INSERT INTO ... ON DUPLICATE KEY UPDATE" syntax, on PHP 5.3.29 and mysql_affected_rows() was returning either 2 for updated row, 1 for inserted new row, and also 0, which was not documented, evidently when nothing was inserted. I was inserting a single row.

down

HMax ¶

17 years ago


If you use "INSERT INTO ... ON DUPLICATE KEY UPDATE" syntax, mysql_affected_rows() will return you 2 if the UPDATE was made (just as it does with the "REPLACE INTO" syntax) and 1 if the INSERT was.

So if you use one SQL request to insert several rows at a time, and some are inserted, some are just updated, you won't get the real count.

down

dobrys at abv dot bg ¶

17 years ago


I see that when try to use mysql_affected_rows() with "mysql_pconnect(...)" without link indetifier as param in "mysql_affected_rows()" the result is allways -1.
When use link identifier "mysql_affected_rows($this_sql_connection)" - everything is Fine. This is is on PHP Version 5.2.0
Hope that this was helpfull for somebody

down

deponti A_T tiscalinet D0T it ¶

21 years ago


It works also for REPLACE query,returning:
0 if the record it's already updated (0 record modified),
1 if the record it's new (1 record inserted),
2 if the record it's updated (2 operations: 1 deletion+ 1 insertion)

down

gtisza at gmail dot com ¶

5 years ago


Note that when the CLIENT_FOUND_ROWS connection flag was used, affected_rows returns the number of rows matched by the WHERE condition of an UPDATE query, even if the query doesn't actually change those rows. I.e. for

     INSERT INTO t(id, val) VALUES (1, 'x');
     UPDATE t SET val = 'x' WHERE id = 1;

the number of affected rows will be 0 normally but 1 with CLIENT_FOUND_ROWS.

down

vitospericolato at gmail dot com ¶

7 years ago


calling mysql_affected_rows(null)
is not the same that calling mysql_affected_rows()

So, if you have a $link variable that could be null, you must write

if($link) 
  $n=mysql_affected_rows($link);
else 
  $n=mysql_affected_rows();

down

-2

brian at smitherconsulting dot com ¶

8 years ago


In the case of INSERT where a row/slot had been previously deleted, making an uncollapsed hole in the table, and the record being inserted fills that empty row/slot, that is to say, the inserted data did not create a new row/slot/space, then this may explain why a zero result is returned by this function.

down

-7

steffen at showsource dot dk ¶

20 years ago


Using OPTIMIZE TABLE will also return true.
So, if you want to check the numbers of deleted records, use mysql_affected_rows() before OPTIMIZE TABLE

down

-10

sean at adtools dot co dot uk ¶

16 years ago


Here's a little function I've been using for a while now, pass it two parameters (action command (1 or 0 see notes)) and a sql statement.



It returns a simple line which shows the length of time taken to action the query, the status of the query (0= query not actioned, you can set this value for testing, 1=success qry executed successfully, -1= failed, there was a problem with the sql statement) the number of lines affected by that query and the sql statement itself. 



I've found this invaluable when trying to tie down large amounts of updates to a table, using this you can easily see where a query was successfully executed and the number of rows are affected, or where there are problems and a statement has failed for example.



<?php

function dosql($action,$sql){

  # assuming you have setup a link to your database entitled $link

  # action = 1 run this query

  # action = 0 don't run, just return sql statement

  

  $start = getmtime();

  

  if($action==1){

    $result = mysql_query($sql);

    $affectedrows = "[".mysql_affected_rows($link)."]";

  } 

  return "[".number_format((getmtime()-$start),3)."][$action]: $sql\n";

  mysql_free_result($result);

}

?>



Example output:

[0.072][1][80]: UPDATE MYTABLE SET FIELD = 1;

[0.106][1][758]: UPDATE ANOTHERTABLE SET FIELD = 2;

[0.006][-1][0]: UPDATER ANOTHERTABLE SET FIELD = 2;



The output shows:



[Timetaken][result]][lines affected]



The result will be either -1, 0 or 1, -1 means there's a problem with the sql statement, 1 means it executed correctly, 0 means it wasn't executed.

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