How to combine JSON_LENGTH and JSON_EXTRACT in MySQL?

mysql json

If you use MySQL 8.0, you can extract the second last json item with:

JSON_EXTRACT(JsonData, '$[last-1]');

mysql json

@len here is a table. You can't automap it to each update row.

You need to inline the length, e.g.

UPDATE MyTable SET ExtractedData = JSON_EXTRACT(JsonData, CONCAT('$[',JSON_LENGTH(JsonData)-1,']'));

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