MySql version 5.6.39

i have one table that now needs to support chinese characters. the other tables in the database do not need utf8mb4 encoding.

what have i done thus far:
1) backed up database!
2) alter table <blah> default character set utf8mb4 collate utf8mb4_unicode_ci;
3) alter table <blah> convert to character set utf8mb4 collate utf8mb4_unicode_ci;
4) (for all columns except numeric) alter table <blah> change col1 col1 varchar(xx) character set utf8mb4 collate utf8mb4_unicode_ci;

what i have not done thus far:
1) alter database <blahDB> character set utf8mb4 collate utf8mb4_unicode_ci;

i've seen several questions/answers here...notibly: How to easily convert utf8 tables to utf8mb4 in MySQL 5.5 Is it necessary to alter the database when all i want is for one table within it to be utf8mb4?

Right now, when i insert a "special" (unicode) char (0x2015) in the middle of a string into the table, it is stored as '?'. Help!!

  • Do the changes to the columns show correctly when investigating the schema? SHOW FULL COLUMNS FROM <blah>;
    – KevH
    Commented Nov 5, 2019 at 15:38
  • Yes! they all (except the "Id" numeric type column) show "utf8mb4_unicode_ci" collation.
    – David M
    Commented Nov 5, 2019 at 15:46
  • How are you interacting with MySQL? If it's via an external client is the connection able to handle the characters? This link may help: [mathiasbynens.be/notes/mysql-utf8mb4]
    – KevH
    Commented Nov 5, 2019 at 16:10
  • i have a java program that issues the relevant sql functions (INSERT, SELECT, etc). Lemme read that article...
    – David M
    Commented Nov 5, 2019 at 16:20

1 Answer 1


Going by what you have to do within a PHP-Webserver environment to use utf8 / utf8mb4, you have up to 5 or more construction places. And you covered 2 of them

  • collation of table and column(s)
  • overwork existing string-data in said columns


  • make sure your application / tool uses the correct collation as well
  • make sure you communicate with the database using the correct collation
  • set the frontend of your application / tool to handle said collation

As JAVA is well prepared I guess its the database connection ...

  • in the Java code i had to convert the offending String to bytes("UTF8") prior to storing in the table. i had to reverse the conversion when i selected the record from the table. It works! thanks!
    – David M
    Commented Nov 6, 2019 at 10:49

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