php - 按字母顺序从列表中获取值作为列表组

ucfirst returns the entire string with the first letter capitalised, you'll need to grab just the first letter with substr first.

$data = [];

while ($row = mysqli_fetch_assoc($result)) {
    extract($row);
    $key = strtoupper($firstname[0]))
    $data[$key][] = $row;
}

To get the output (roughly) like you want, try something like:

foreach ($data as $letter => $rows)
{
    echo "<h1>{$letter}</h1>", PHP_EOL;

    foreach ($rows as $row)
    {
        echo "<p>{$row['firstname']} {$row['lastname']}</p>", PHP_EOL;
    }
}

Your attempt will not do what you want. To achieve this, you will have to create a nested array, then on each iteration check the first letter of the firstname. Check if that letter already exists as a key in the array, and create an item in your array with an empty array as its value, it if it doesn't, and then add the row data to it to that newly created empty array.

$data = [];
while ($row = mysqli_fetch_assoc($result)) {
    $firstLetter = strtoupper($row["firstname"][0]); // convert to upper case so all are the same
    if (array_key_exists($firstLetter, $data) === false) $data[$firstLetter] = [];
    // now just add the row data:
    $data[$firstLetter][] = $row;
}

First use Order in your MySQL Query: ... ORDER BY firstname ASC

Create Arrays for Alphabets using PHP:

$Alphabetic_Array = array();

while ($row = mysqli_fetch_assoc($result)) {
    $Alphabetic_Array[$row['firstname'][0]][] = $row;
}

First of all, I suggest you to sort records in your query, otherwise you have to sort resulting array before grouping it:

    SELECT * from tablename
  ORDER BY firstname ASC, lastname ASC

Then, you can use array_map to group your array:

$result = array();
array_map
(
    function( $row ) use( &$result )
    {
        $result[strtoupper(substr($row['firstname'],0,1))][] = $row;
    },
    $data
);

(Note that we have to call $result by reference)

Now the $result is an array like this:

Array
(
    [B] => Array
        (
            [0] => Array
                (
                    [id] => 7
                    [firstname] => bon
                    [lastname] => doe
                )
            [1] => Array
                (
                    [id] => 6
                    [firstname] => Bon
                    [lastname] => Jone
                )
        )
    [H] => Array
        (
            [0] => Array
                (
                    [id] => 1
                    [firstname] => Hassan
                    [lastname] => Ilyas
                )
        )
    [J] => Array
        (
            [0] => Array
                (
                    [id] => 5
                    [firstname] => John
                    [lastname] => Doe
                )
        )
)

If you want/can use PDO instead of mysqli_, you can obtain desired result directly from MySQL query. Set your query in this way:

    SELECT UPPER(SUBSTR(firstname,1,1)) as initial, tablename.* from tablename
  ORDER BY firstname ASC, lastname ASC

and then, fetching in in this way:

$data->fetchAll( PDO::FETCH_ASSOC|PDO::FETCH_GROUP );

your $data will contain desired array, without need of additional processing. The PDO::FETCH_GROUP option groups fetched results by first column returned by query, in your case the capitalized firstname first letter.

What about letting MYSQL do the logic?

SELECT * FROM users_table, SUBSTRING(firstName, 1, 1) as initial ORDER BY firstname ASC

Then you just can append each line to an array

while ($row = mysqli_fetch_assoc($result)) {
    $Alphabetic_Array[$row['initial'] = $row;
}

It's just pseudo code but I think the idea is pretty clear

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