How can I query in Japanese on Rails active record?

Question

I want to query in Japanese on Ruby on Rails. In my current code, it is not working and only returns an empty set. The database, MYSQL 8.0 is running on docker with the default setting. Should I update MYSQL configuration?

Here's my select query and the schema.

Active record query

@internships = Internship.where("subject LIKE :keyword OR content LIKE :keyword", keyword: params[:keyword]).all

Schema

create_table "internships", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci" do |t|
    t.date "start_date"
    t.date "end_date"
    t.integer "employment_number"
    t.bigint "company_id"
    t.text "content"
    t.string "subject"
    t.integer "job_type"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.date "deadline_date"
    t.text "summary"
    t.index ["company_id"], name: "index_internships_on_company_id"
  end

MYSQL charset

mysql> SHOW VARIABLES LIKE 'char%';
+--------------------------+--------------------------------+
| Variable_name            | Value                          |
+--------------------------+--------------------------------+
| character_set_client     | latin1                         |
| character_set_connection | latin1                         |
| character_set_database   | utf8                           |
| character_set_filesystem | binary                         |
| character_set_results    | latin1                         |
| character_set_server     | utf8mb4                        |
| character_set_system     | utf8                           |
| character_sets_dir       | /usr/share/mysql-8.0/charsets/ |
+--------------------------+--------------------------------+
8 rows in set (0.01 sec)

Thank you in advance.

Answer 1

UTF-8

UTF-8 is an encoding for the Unicode character set, which supports pretty much every language in the world.

The only difference comes with sorting your results, different letters might come in a different order in other languages. Also, comparing a to ä might behave differently in another collation.

utf8mb4_unicode_ci

For a BMP character, utf8 and utf8mb4 have identical storage characteristics: same code values, same encoding, same length

For a supplementary character, utf8 cannot store the character at all, while utf8mb4 requires four bytes to store it. Since utf8 cannot store the character at all, you do not have any supplementary characters in utf8 columns and you need not worry about converting characters or losing data when upgrading utf8 data from older versions of MySQL.

So you better change your
character_set_client, character_set_connection, character_set_results to utf8mb4

Solution:

For Database:

ALTER DATABASE database_name CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;

For Table:

ALTER TABLE table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

For column:

ALTER TABLE table_name CHANGE column_name column_name VARCHAR(191) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

Change Configuration file my.cnf

> vim /etc/my.cnf
# 
[client]
default-character-set = utf8mb4

# 
[mysql]
default-character-set = utf8mb4

# 
[mysqld]
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci

> service mysqld restart