show variables like '%collation%';
+----------------------+-------------+
| Variable_name        | Value       |
+----------------------+-------------+
| collation_connection | utf8mb4_bin |
| collation_database   | utf8mb4_bin |
| collation_server     | utf8mb4_bin |
+----------------------+-------------+
3 rows in set (0.001 sec)

select * from information_schema.schemata where schema_name = 'base'\G
*************************** 1. row ***************************
              CATALOG_NAME: def
               SCHEMA_NAME: base
DEFAULT_CHARACTER_SET_NAME: utf8mb4
    DEFAULT_COLLATION_NAME: utf8mb4_bin
                  SQL_PATH: NULL
1 row in set (0.000 sec)

select * from information_schema.tables where table_schema = 'base' and table_name = 't_config'\G
*************************** 1. row ***************************
   TABLE_CATALOG: def
    TABLE_SCHEMA: base
      TABLE_NAME: t_config
      TABLE_TYPE: BASE TABLE
          ENGINE: InnoDB
         VERSION: 10
      ROW_FORMAT: Dynamic
      TABLE_ROWS: 5526
  AVG_ROW_LENGTH: 284
     DATA_LENGTH: 1572864
 MAX_DATA_LENGTH: 0
    INDEX_LENGTH: 491520
       DATA_FREE: 4194304
  AUTO_INCREMENT: NULL
     CREATE_TIME: 2020-01-21 11:49:39
     UPDATE_TIME: 2020-04-09 10:44:03
      CHECK_TIME: NULL
 TABLE_COLLATION: utf8mb4_bin
        CHECKSUM: NULL
  CREATE_OPTIONS: 
   TABLE_COMMENT: 1.0.0: configuration information for all applications
MAX_INDEX_LENGTH: 0
       TEMPORARY: N
1 row in set (0.000 sec)

select cdgrp,tshort,tlong from t_config where tshort = 'xau';
+----------+--------+-------+
| cdgrp    | tshort | tlong |
+----------+--------+-------+
| Currency | XAU    | Gold  |
+----------+--------+-------+
1 row in set (0.005 sec)

alter table t_config convert to character set utf8mb4 collate utf8mb4_bin;
Query OK, 0 rows affected (0.066 sec)
Records: 0  Duplicates: 0  Warnings: 0

select cdgrp,tshort,tlong from t_config where tshort = 'xau';
Empty set (0.006 sec)