mysqli_stmt::$affected_rows()

(PHP 5, PHP 7)

Returns the total number of rows changed, deleted, or inserted by the last executed statement

说明

面向对象风格
int $mysqli_stmt->affected_rows;

过程化风格
mysqli_stmt_affected_rows(mysqli_stmt$stmt): int

Returns the number of rows affected byINSERT,UPDATE, orDELETEquery.

This function only works with queries which update a table. In order to get the number of rows from a SELECT query, use mysqli_stmt_num_rows() instead.

参数

$stmt

仅以过程化样式：由mysqli_stmt_init()返回的 statement 标识。

返回值

An integer greater than zero indicates the number of rows affected or retrieved. Zero indicates that no records where updated for an UPDATE/DELETE statement, no rows matched the WHERE clause in the query or that no query has yet been executed.-1 indicates that the query has returned an error. NULL indicates an invalid argument was supplied to the function.

Note:

If the number of affected rows is greater than maximal PHP int value, the number of affected rows will be returned as a string value.

范例

Example #1 面向对象风格

<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
/* create temp table */
$mysqli->query("CREATE TEMPORARY TABLE myCountry LIKE Country");
$query = "INSERT INTO myCountry SELECT * FROM Country WHERE Code LIKE ?";
/* prepare statement */
if ($stmt = $mysqli->prepare($query)) {
    /* Bind variable for placeholder */
    $code = 'A%';
    $stmt->bind_param("s", $code);
    /* execute statement */
    $stmt->execute();
    printf("rows inserted: %d\n", $stmt->affected_rows);
    /* close statement */
    $stmt->close();
}
/* close connection */
$mysqli->close();
?>

Example #2 过程化风格

<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
/* create temp table */
mysqli_query($link, "CREATE TEMPORARY TABLE myCountry LIKE Country");
$query = "INSERT INTO myCountry SELECT * FROM Country WHERE Code LIKE ?";
/* prepare statement */
if ($stmt = mysqli_prepare($link, $query)) {
    /* Bind variable for placeholder */
    $code = 'A%';
    mysqli_stmt_bind_param($stmt, "s", $code);
    /* execute statement */
    mysqli_stmt_execute($stmt);
    printf("rows inserted: %d\n", mysqli_stmt_affected_rows($stmt));
    /* close statement */
    mysqli_stmt_close($stmt);
}
/* close connection */
mysqli_close($link);
?>

以上例程会输出：

rows inserted: 17

参见

• mysqli_stmt_num_rows() Return the number of rows in statements result set
• mysqli_prepare() 准备执行一个 SQL 语句

It appears that an UPDATE prepared statement which contains the same data as that already in the database returns 0 for affected_rows. I was expecting it to return 1, but it must be comparing the input values with the existing values and determining that no UPDATE has occurred.

I find should add $stmt->store_result() after $stmt->execute(), otherwise you can't get right results when use $stmt->affected_rows

I'm not sure whether or not this is the intended behavior, but I noticed through testing that if you were to use transactions and prepared statements together and you added a single record to a database using a prepared statement, but later rolled it back, mysqli_stmt_affected_rows will still return 1.