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# mysql_affected_rows

(PHP 3, PHP 4 , PHP 5)

mysql_affected_rows -- Get number of affected rows in previous MySQL operation

## Description

int mysql_affected_rows ( [resource link_identifier] )

mysql_affected_rows() returns the number of rows affected by the last INSERT, UPDATE or DELETE query associated with link_identifier. If the link identifier isn't specified, the last link opened by mysql_connect() is assumed.

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

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.

> 注: 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.

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

If the last query failed, this function will return -1.

範例 1. Delete-Query
`<?php /* connect to database */ $link = mysql_connect('localhost', 'mysql_user', 'mysql_password'); if (!$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()); ?>`
The above example would produce the following output:
    Records deleted: 10
    Records deleted: 0

範例 2. Update-Query
`<?php /* connect to database */ mysql_connect("localhost", "mysql_user", "mysql_password") or 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"); ?>`
The above example would produce the following output:
    Updated Records: 10

See also mysql_num_rows(), and mysql_info().

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