mysqli_result::fetch_assoc
mysqli_fetch_assoc
(PHP 5, PHP 7, PHP 8)
mysqli_result::fetch_assoc -- mysqli_fetch_assoc — Fetch the next row of a result set as an associative array
说明
面向对象风格
过程化风格
Fetches one row of data from the result set and returns it as an associative
array.
Each subsequent call to this function will return the next row within the
result set, or null if there are no more rows.
If two or more columns of the result have the same name, the last column will take precedence and overwrite any previous data. To access multiple columns with the same name, mysqli_fetch_row() may be used to fetch the numerically indexed array, or aliases may be used in the SQL query select list to give columns different names.
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 mysqli_result 对象。
返回值
Returns an associative array representing the fetched row,
where each key in the array represents the name of one of the result
set's columns, null if there
are no more rows in the result set, 或者在失败时返回 false.
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
- mysqli_fetch_array() - Fetch the next row of a result set as an associative, a numeric array, or both
- mysqli_fetch_column() - Fetch a single column from the next row of a result set
- mysqli_fetch_row() - Fetch the next row of a result set as an enumerated array
- mysqli_fetch_object() - Fetch the next row of a result set as an object
- mysqli_query() - 对数据库执行一次查询
- mysqli_data_seek() - Adjusts the result pointer to an arbitrary row in the result
add a note
User Contributed Notes 5 notes
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
)
)
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.
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
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'}
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
备份地址：http://www.lvesu.com/blog/php/mysqli-result.fetch-assoc.php