International PHP Conference Munich 2021

mysqli_result::fetch_assoc

mysqli_fetch_assoc

(PHP 5, PHP 7)

mysqli_result::fetch_assoc -- mysqli_fetch_assocFetch a result row as an associative array

说明

面向对象风格

public mysqli_result::fetch_assoc(): array|null|false

过程化风格

mysqli_fetch_assoc(mysqli_result $result): array|null|false

Returns an associative array that corresponds to the fetched row or null if there are no more rows.

注意: 此函数返回的字段名大小写敏感

注意: 此函数将 NULL 字段设置为 PHP null 值。

参数

result

仅以过程化样式:由 mysqli_query()mysqli_store_result()mysqli_use_result()mysqli_stmt_get_result() 返回的结果集标识。

返回值

Returns an associative array of values representing the fetched row in the result set, where each key in the array represents the name of one of the result set's columns or null if there are no more rows in result set.

If two or more columns of the result have the same field names, the last column will take precedence. To access the other column(s) of the same name, you either need to access the result with numeric indices by using mysqli_fetch_row() or add alias names.

范例

示例 #1 mysqli_result::fetch_assoc() example

面向对象风格

<?php

mysqli_report
(MYSQLI_REPORT_ERROR MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost""my_user""my_password""world");

$query "SELECT Name, CountryCode FROM City ORDER BY ID DESC";

$result $mysqli->query($query);

/* fetch associative array */
while ($row $result->fetch_assoc()) {
    
printf("%s (%s)\n"$row["Name"], $row["CountryCode"]);
}

过程化风格

<?php

mysqli_report
(MYSQLI_REPORT_ERROR MYSQLI_REPORT_STRICT);
$mysqli mysqli_connect("localhost""my_user""my_password""world");

$query "SELECT Name, CountryCode FROM City ORDER BY ID DESC";

$result mysqli_query($mysqli$query);

/* fetch associative array */
while ($row mysqli_fetch_assoc($result)) {
    
printf("%s (%s)\n"$row["Name"], $row["CountryCode"]);
}

以上例程的输出类似于:

Pueblo (USA)
Arvada (USA)
Cape Coral (USA)
Green Bay (USA)
Santa Clara (USA)

示例 #2 Comparison of mysqli_result iterator and mysqli_result::fetch_assoc() usage

mysqli_result can be iterated using foreach. The result set will always be iterated from the first row, regardless of the current position.

<?php

mysqli_report
(MYSQLI_REPORT_ERROR MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost""my_user""my_password""world");

$query 'SELECT Name, CountryCode FROM City ORDER BY ID DESC';

// Using iterators
$result $mysqli->query($query);
foreach (
$result as $row) {
    
printf("%s (%s)\n"$row["Name"], $row["CountryCode"]);
}

echo 
"\n==================\n";

// Not using iterators
$result $mysqli->query($query);
while (
$row $result->fetch_assoc()) {
    
printf("%s (%s)\n"$row["Name"], $row["CountryCode"]);
}

以上例程的输出类似于:

Pueblo (USA)
Arvada (USA)
Cape Coral (USA)
Green Bay (USA)
Santa Clara (USA)

==================
Pueblo (USA)
Arvada (USA)
Cape Coral (USA)
Green Bay (USA)
Santa Clara (USA)

参见

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User Contributed Notes 5 notes

up
76
Miller
7 years ago
I often like to have my results sent elsewhere in the format of an array (although keep in mind that if you just plan on traversing through the array in another part of the script, this extra step is just a waste of time).

This is my one-liner for transforming a mysqli_result set into an array.
<?php
$sql
= new MySQLi($host, $username, $password, $database);

$result = $sql->query("SELECT * FROM `$table`;");
for (
$set = array (); $row = $result->fetch_assoc(); $set[] = $row);
print_r($set);
?>

Outputs:
Array
(
    [0] => Array
        (
            [id] => 1
            [field2] => a
            [field3] => b
        ),
    [1] => Array
        (
            [id] => 2
            [field2] => c
            [field3] => d
        )
)

I use other variations to adapt to the situation, i.e. if I am selecting only one field:
<?php
$sql
= new MySQLi($host, $username, $password, $database);
$result = $sql->query("SELECT `field2` FROM `$table`;");
for (
$set = array (); $row = $result->fetch_assoc(); $set[] = $row['field2']);
print_r($set);
?>
Outputs:
Array
(
    [0] => a
    [1] => c
)

Or, to make the array associative with the primary index (code assumes primary index is the first field in the table):
<?php
$sql
= new MySQLi($host, $username, $password, $database);
$result = $sql->query("SELECT * FROM `$table`;");
for (
$set = array (); $row = $result->fetch_assoc(); $set[array_shift($row)] = $row);
print_r($set);
?>
Outputs:
Array
(
    [1] => Array
        (
            [field2] => a
            [field3] => b
        ),
    [2] => Array
        (
            [field2] => c
            [field3] => d
        )
)
up
24
james dot phx at gmail dot com
9 years ago
IMPORTANT NOTE:

If you were used to using code like this:

<?php
while(false !== ($row = mysql_fetch_assoc($result)))
{
   
//...
}
?>

You must change it to this for mysqli:

<?php
while(null !== ($row = mysqli_fetch_assoc($result)))
{
   
//...
}
?>

The former will cause your script to run until max_execution_time is reached.
up
-15
gilles dot falquet at unige dot ch
3 years ago
Be careful when using fetch_assoc instead of fetch_row. If two columns of the result have the same column name, even if they are prefixed with different table names in the query, only one of them will be retained in the result. This is because the prefix is dropped (either by mysql or by this function)

For example if the query is

     select p1.name, p2.name
     from person p1, friend, person p2
     where p1.id = friend.person1 and p2.id = friend.person2

the arrays returned by fetch_assoc will be of the form

{'name' => 'bob'}
{'name' => 'anna'}

and not (as expected)

{'p1.name' => 'bob', 'p2.name' => 'alice'}
{'p1.name' => 'anna', 'p2.name' => 'irla'}
up
-14
paul dot allsopp at inseego dot com
4 years ago
The official example given here breaks a cardinal rule, and should be rectified.

while ($row = $result->fetch_assoc())...

...breaks the rule of "assignment in condition".

while (($x = $y->getZ()) !== false) or
while (($x = $y->getZ()) !== null)

...is the correct syntax.

Conditional statements should always check for a boolean
up
-25
Hesham Mohamed Sediek
6 years ago
when you fetch the data from the query variable
and try to fetch it again in another part of the script
from the same query variable ,
when you try to echo all data you have fetched,
it will not echo the data you have used in the first fetch
(it will exceed the results you have used in the first fetch).......

Example :
<?php
$connect
= new mysqli("localhost","root","root","elshamy")
or die (
mysqli_error());

$query=$connect->query("SELECT * FROM users ORDER BY id ASC");

$first_fetch=$query->fetch_array(MYSQLI_ASSOC);
echo
$first_fetch['id']."===>".$first_fetch['user_name']."\n--------------------\n";

while(
$row=$query->fetch_array(MYSQLI_ASSOC)){

/*it will exceed the first
id&user_name value that
you have use in the first fetch*/

echo $row['id']."  ".$row['user_name']."<br/>";
}
?>

above example will echo :
1===>userA
------------------------
2===>userB
3===>userC
4===>userD
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