TOP_LEVEL_DOMAIN

Description

The TOP_LEVEL_DOMAIN function is used to extract the top-level domain from a URL. If the input URL is invalid, it returns an empty string.

Syntax

TOP_LEVEL_DOMAIN(<url>)

Parameters

Parameter	Description
<url>	The URL string from which to extract the top-level domain. Type: VARCHAR

Return Value

Returns VARCHAR type, representing the extracted top-level domain.

Special cases:

• Returns NULL if url is NULL
• Returns an empty string if url is not a valid URL format
• For multi-level domains (e.g., .com.cn), returns the last level domain

Examples

1. Basic domain processing

SELECT top_level_domain('www.baidu.com');

+-----------------------------------+
| top_level_domain('www.baidu.com') |
+-----------------------------------+
| com                               |
+-----------------------------------+

2. Multi-level domain processing

SELECT top_level_domain('www.google.com.cn');

+---------------------------------------+
| top_level_domain('www.google.com.cn') |
+---------------------------------------+
| cn                                    |
+---------------------------------------+

3. Invalid URL processing

SELECT top_level_domain('wwwwwwww');

+------------------------------+
| top_level_domain('wwwwwwww') |
+------------------------------+
|                              |
+------------------------------+