Validate URL

The is_valid_url function checks whether a string is a well-formed URL with a scheme, authority (host), and optional port/path/query/fragment. Returns a BOOLEAN.

A valid URL must have:

• A scheme (e.g., http, https, ftp, or any valid scheme)

• The :// separator

• A non-empty host (domain name, IPv4, or bracketed IPv6)

D SELECT is_valid_url('https://example.com') AS valid;
┌─────────┐
│  valid  │
│ boolean │
├─────────┤
│ true    │
└─────────┘

D SELECT is_valid_url('https://example.com:8080/path?q=1#frag') AS valid;
┌─────────┐
│  valid  │
│ boolean │
├─────────┤
│ true    │
└─────────┘

D SELECT is_valid_url('not a url') AS valid;
┌─────────┐
│  valid  │
│ boolean │
├─────────┤
│ false   │
└─────────┘

D SELECT is_valid_url('example.com') AS valid;
┌─────────┐
│  valid  │
│ boolean │
├─────────┤
│ false   │
└─────────┘

Returns NULL for NULL input.