Mysql, initialisation colonne sortKey en fonction d'une colonne label dans l'ordre des labels

set @fieldId := (select id from ruleFields where name='TYPE_CLIENT');

set @sortKey := (select sortKey from ruleFieldValues where id_rule_field=@fieldId AND NAME is NULL);

UPDATE ruleFieldValues SET sortKey=@sortKey+2 WHERE id_rule_field=@fieldId AND NAME is NULL;

REPLACE INTO ruleFieldValues (name, id_rule_field, label, sortKey, tooltip) VALUES
  ('CustomerForDeviceLoan', @fieldId, 'Airbox', @sortKey, 'CustomerForDeviceLoan'),
  ('CustomerForBlister', @fieldId, 'Blister', @sortKey+1, 'CustomerForBlister');

SET @row_num := 0;

UPDATE ruleFieldValues
    INNER JOIN (
    SELECT id, @row_num := @row_num + 1 AS row_num
    FROM ruleFieldValues
    WHERE id_rule_field=@fieldId AND NAME is not NULL
    ORDER BY label ASC
    ) AS temp_table
ON ruleFieldValues.id = temp_table.id
SET ruleFieldValues.sortKey = temp_table.row_num;

SET @maximum := (select max(sortKey) from ruleFieldValues WHERE id_rule_field=@fieldId AND NAME is not NULL);

UPDATE ruleFieldValues SET sortKey=@maximum+1  WHERE id_rule_field=@fieldId AND NAME is NULL;