Is it possible to have a unique tuple constraint in MariaDB that uses specific values?

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In a MariaDB 10.1 table of 50 columns, I have two columns "code" which is a sequence of 13 random characters and "maxversion" which is a tinyint boolean (0 or 1).

Is it possible to add a unique key or a constraint that says for each code, only one row can have a maxversion = 1? Keep in mind that it should still be allowed to have many rows with the same code and maxversion = 0.

Examples :

This is allowed :

code          | maxversion
123456789abcd | 1
123456789abcd | 0
123456789abcd | 0
123456789abcd | 0
dcba987654321 | 1
dcba987654321 | 0
dcba987654321 | 0

This is not allowed :

code          | maxversion
123456789abcd | 1
123456789abcd | 1
123456789abcd | 0
123456789abcd | 0
dcba987654321 | 1
dcba987654321 | 0
dcba987654321 | 0

I suppose this is possible through triggers, but is there anyway to achieve this in a cleaner and more concise way ?



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