The Ultimate Guide to High Availability with MariaDB

Comments - Dynamic Columns

9 years, 8 months ago Olivier Bertrand
Create Dynamic column does not work in SELECT

Using the table:

CREATE TABLE `person` ( `id` int(11) NOT NULL AUTO_INCREMENT, `fname` varchar(255) NOT NULL, `lname` varchar(255) NOT NULL, `car_make` varchar(255) DEFAULT NULL, `car_model` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`) ) engine=MYISAM;

This works:

SELECT COLUMN_JSON(COLUMN_CREATE('first_name', fname, 'last_name', lname, 'car', COLUMN_CREATE('make', car_make, 'model', car_model))) AS person_data FROM person WHERE id = 57;

But this returns junks:

SELECT COLUMN_CREATE('first_name', fname, 'last_name', lname) AS person_data, COLUMN_CREATE('make', car_make, 'model', car_model) AS car_data FROM person WHERE id = 57;

Why? Or what's wrong in it?

 
9 years, 8 months ago Ian Gilfillan
Re: Create Dynamic column does not work in SELECT

COLUMN_CREATE() returns a dynamic column blob, which is suitable for storing in a table, or for use with another function as you did in your first example, but not for SELECTing on its own.

 
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