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原创 SQL常用初级函数

示例：select score,case when score >= 90 then 'A' when score >= 80 then 'B' when score >= 70 then 'C' when score >= 60 then 'D' else 'F' end as grade from students;示例：select case region when '北京' then '中国' when '华盛顿' then '美国' end as nations from map。