Mariadb query utf8 escaped string - mysql

Question

I am using 5.5.65-MariaDB MariaDB Server.
I have a table with a column of type medium text, named "remoteData", where I store a json string.
String values in this json string are stored as escaped utf8 sequences, for example
"patientFirstName":"\u0395\u039b\u0395\u03a5\u0398\u0395\u03a1\u0399\u039f\u03a3"
The above value is the Greek Name "ΕΛΕΥΘΕΡΙΟΣ".
I am trying to search this column using the query
Select * from sync_details where remoteData like "%ΛΕΥΘΕΡ%"
but I get an empty set.
I assume this is because of the values being escaped but I don't know what to do.
EDIT: The query will run through php so we can use a solution that includes php functions.
Thank you in advance.
Christoforos

Answer 1

With a database defined to use CHARACTER SET utf8and a utf8_general_ci collation it should just work like this:
CREATE DATABASE IF NOT EXISTS `test` CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE TABLE `test`.`sync_details` (`remoteData` MEDIUMTEXT);
INSERT INTO `test`.`sync_details` (`remoteData`) VALUES ('{"patientFirstName":"\\u0395\\u039b\\u0395\\u03a5\\u0398\\u0395\\u03a1\\u0399\\u039f\\u03a3"}');
SELECT `remoteData` FROM `test`.`sync_details` WHERE `remoteData` LIKE '%ΛΕΥΘΕΡ%';
+----------------------------------------------+
| remoteData |
+----------------------------------------------+
| {"patientFirstName": "ΕΛΕΥΘΕΡΙΟΣ"} |
+----------------------------------------------+
1 row in set (0,00 sec)
You could also try JSON_EXTRACT to get structured data from the stored JSON object. I just tested it like this:
SELECT JSON_EXTRACT(`remoteData`, "$.patientFirstName")
FROM `test`.`sync_details`
WHERE JSON_EXTRACT(`remoteData`, "$.patientFirstName")
LIKE '%ΛΕΥΘΕΡ%';
+--------------------------------------------------+
| JSON_EXTRACT(`remoteData`, "$.patientFirstName") |
+--------------------------------------------------+
| "ΕΛΕΥΘΕΡΙΟΣ" |
+--------------------------------------------------+
1 row in set (0,00 sec)
To index data in the JSON object you could add a "Generated Column" to your table using the GENERATED ALWAYS syntax
ALTER TABLE `test`.`sync_details` ADD COLUMN `firstName` VARCHAR(100) GENERATED ALWAYS AS (`remoteData` ->> '$.patientFirstName');
CREATE INDEX `firstnames_idx` ON `test`.`sync_details`(`firstName`);
SELECT `firstName` FROM `test`.`sync_details` WHERE `firstName` LIKE '%ΛΕΥΘΕΡ%';
+----------------------+
| firstName |
+----------------------+
| ΕΛΕΥΘΕΡΙΟΣ |
+----------------------+
1 row in set (0,00 sec)
This will only work with MariaDB >= 10.2 and with a utf8 encoded db and a utf8_general_ci collation.