Why Am I Only Accessing the First Value in My MySQLi Result Set?

Iterating Over Result Sets in MySQLi

When working with result sets in MySQLi, you may encounter an issue where only the first value is accessible during iteration. This typically arises from using fetch_array() and improper understanding of its behavior.

Default Behavior of fetch_array()

By default, fetch_array() returns an array with both indexed and associative keys, known as MYSQLI_BOTH. To specify a result set with only indexed or associative keys, use MYSQLI_NUM or MYSQLI_ASSOC, respectively.

Alternatives to fetch_array()

Rather than relying on fetch_array(), consider more efficient and concise alternatives:

• Associative Arrays (MYSQLI_ASSOC): Access values using the column name as a key:

while ($row = $output->fetch_array(MYSQLI_ASSOC)) {
    echo $row['uid'];
}

• Indexed Arrays (MYSQLI_NUM): Access values by index:

while ($row = $output->fetch_array(MYSQLI_NUM)) {
    echo $row[0];
}

• Object-Oriented Iteration: Iterate over the result set as an iterable object, omitting the need for fetch_array():

foreach ($output as $row) {
    echo $row['uid'];
}

Troubleshooting Iteration

Using $i to increment through indexed keys is not suitable for result sets with associative keys. For example, the result set may have values in the following structure:

[
    0 => [0 => 1, 'uid' => 1],
    1 => [0 => 2, 'uid' => 2],
    2 => [0 => 3, 'uid' => 3]...
]

In this scenario, $row[1] will not exist in subsequent iterations, leading to the issue.

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