.. change::
    :tags: bug, mysql, regression
    :tickets: 7518

    Fixed regression caused by :ticket:`7518` where changing the syntax "SHOW
    VARIABLES" to "SELECT @@" broke compatibility with MySQL versions older
    than 5.6, including early 5.0 releases. While these are very old MySQL
    versions, a change in compatibility was not planned, so version-specific
    logic has been restored to fall back to "SHOW VARIABLES" for MySQL server
    versions < 5.6.
