how to check mysql server installed or not code example

Example 1: find mysql version linux

SHOW VARIABLES LIKE "%version%";
+-------------------------+------------------------------------------+
| Variable_name           | Value                                    |
+-------------------------+------------------------------------------+
| protocol_version        | 10                                       |
| version                 | 5.0.27-standard                          |
| version_comment         | MySQL Community Edition - Standard (GPL) |
| version_compile_machine | i686                                     |
| version_compile_os      | pc-linux-gnu                             |
+-------------------------+------------------------------------------+
5 rows in set (0.04 sec)

Example 2: what is my mysql version

Mysql version
mysql -V