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i have this database with tables bellow. it was running good , till when i have done this code

 alter table <some_table> convert to character set utf8 collate utf8_unicode_ci;

to change collation and the website is down and showed this error:

Illegal mix of collations for operation 'UNION'

, now i dont know what to do . if i will continue to convert all tables , or no . i have also converted the database to utf8 . i should backup my database but its too late. any rollback for this or is there a fix ? thanks.

articles            InnoDB  utf8_unicode_ci     48.0 KiB    -
authentications     InnoDB  utf8_general_ci     32.0 KiB    -
comments            MyISAM  utf8_unicode_ci     3.3 KiB     -
favorites           InnoDB  latin1_swedish_ci   16.0 KiB    -
login_attempts      InnoDB  latin1_swedish_ci   16.0 KiB    -
members             InnoDB  utf8_unicode_ci     48.0 KiB    -
member_setting      InnoDB  latin1_swedish_ci   16.0 KiB    -
messages            MyISAM  latin1_swedish_ci   2.7 KiB     -
page_views          InnoDB  utf8_unicode_ci     16.0 KiB    -
reports             MyISAM  latin1_swedish_ci   1.0 KiB     -
users               InnoDB  utf8_general_ci     16.0 KiB    -
videos              InnoDB  utf8_unicode_ci     80.0 KiB    -
viewer_info         InnoDB  latin1_swedish_ci   64.0 KiB    -
13 tables           MyISAM  utf8_general_ci     359.0 KiB   0 B

EDIT: where there is utf8_unicode_ci its this table i have converted.

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