mysql_affected_rows
(PHP 4, PHP 5, PECL mysql:1.0)
mysql_affected_rows — Get number of affected rows in previous MySQL operation
說明
Get the number of affected rows by the last INSERT, UPDATE, REPLACE or DELETE query associated with link_identifier .
參數
- link_identifier
-
MySQL 的連接識別符。如果沒有指定，預設使用最後被 mysql_connect() 打開的連接。如果沒有找到該連接，函式會嘗試呼叫 mysql_connect() 建立連接並使用它。如果發生意外，沒有找到連接或無法建立連接，系統發出 E_WARNING 級別的警告信息。
Return值
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.
範例
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());
?>
上例的輸出類似於：
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");
?>
上例的輸出類似於：
Updated Records: 10
註釋
Note: Transactions If you are using transactions, you need to call mysql_affected_rows() after your INSERT, UPDATE, or DELETE query, not after the COMMIT.
Note: SELECT Statements To retrieve the number of rows returned by a SELECT, it is possible to use mysql_num_rows().