What are some common methods for generating unique IDs in PHP, specifically for use in e-card scripts?

When generating unique IDs in PHP for use in e-card scripts, it is important to ensure that the generated IDs are truly unique to avoid any conflicts or duplicates. One common method to achieve this is by using the `uniqid()` function in PHP, which generates a unique identifier based on the current time in microseconds. Another approach is to combine `uniqid()` with `md5()` or `sha1()` hashing functions to further increase the uniqueness of the generated IDs.

// Generate a unique ID using uniqid()
$unique_id = uniqid();

// Generate a unique ID using uniqid() and md5 hashing
$unique_id_md5 = md5(uniqid());

// Generate a unique ID using uniqid() and sha1 hashing
$unique_id_sha1 = sha1(uniqid());