usky-website/web/phpMyAdmin/templates/sql/set_column.twig

{% set values_amount = values|length %}
{% set selected_values = current_values|split(',') %}
<select size="{{ values_amount < 10 ? values_amount : 10 }}" multiple>
  {% for value in values %}
    <option value="{{ value }}"{{ value in selected_values ? ' selected' }}>{{ value }}</option>
  {% endfor %}
</select>