Access????(日期自增实现)

现有一字段word,初值为10(数字)，每隔一天值自动减1，如果值<=0，
值就为0。谢谢？？？
怎样实现

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U can define an new column worddt as a datetime, then set the default value is DateAdd('d',10,Now()).
Following,U can get word as :
SELECT iif(datediff("d",now(),worddt)<0,0, datediff("d",now(),worddt)) as word
FROM tb;