学步园

//闰年最直接的判断是:能被4整除且不能被100整除，或者能被400整除的年份<br /> create or replace procedure pro_leap_year(year_in in number)<br /> as<br /> v_mod1 number(4) :=mod(year_in,4);<br /> v_mod2 number(4) :=mod(year_in,100);<br /> v_mod3 number(4) :=mod(year_in,400);<br /> begin<br /> if ((v_mod1=0 and v_mod2<>0) or v_mod3=0) then<br /> dbms_output.put_line(year_in||' is a leap year');<br /> else dbms_output.put_line(year_in||' is not a leap year');<br /> end if;</p> <p> exception<br /> when others then<br /> dbms_output.put_line(sqlerrm);<br /> end pro_leap_year;<br /> /<br /> SQL> exec pro_leap_year(2010);<br /> 2010 is not a leap year<br /> PL/SQL procedure successfully completed<br /> //<br /> SQL> exec pro_leap_year(2000);<br /> 2000 is a leap year<br /> PL/SQL procedure successfully completed<br /> //<br /> //关于闰年平年，下面有一个比较全面的解释：<br /> //在公历（格里历）纪年中，有闰日的年份叫闰年，一般年份365天，闰年为366天。<br /> //由于地球绕太阳运行周期为365天5小时48分46秒（合365.24219天）即一回归年，公历把一年定为365天。<br /> //所余下的时间约为四年累计一天，加在二月里，所以平常年份每年365天，二月为28天，闰年为366天，二月为29天。<br /> //因此，每400年中有97个闰年，闰年在2月末增加一天，闰年366天。<br /> //闰年的计算方法：公元纪年的年数可以被四整除，即为闰年；<br /> //被100整除而不能被400整除为平年；被100整除也可被400整除的为闰年。<br /> //如2000年是闰年，而1900年不是。<br /> //<br /> //我们所关心的是怎么样计算指定的一个年份是否是闰年：<br /> //从上面的描述中，我们知道：<br /> //如果一年中2月份有29天，那么这一年就是闰年，否则是平年<br /> SQL> drop procedure pro_leap_year;<br /> Procedure dropped<br /> //<br /> create or replace procedure pro_leap_year(year_in in number)<br /> as<br /> v_year_in varchar2(10) :=to_char(year_in)||'0229';<br /> v_date date;<br /> begin<br /> //这里将拼接的字符串转换为日期，并赋值给一个日期类型的变量，<br /> //其实就是为了和日期类型进行比较，隐式的比较，比较你输入的年份中2月是否含有29日这一天<br /> v_date :=to_date(v_year_in,'yyyy-mm-dd');<br /> dbms_output.put_line(year_in||' is a leap year');<br /> exception<br /> when others then<br /> dbms_output.put_line(year_in||' is not a leap year');<br /> end pro_leap_year;<br /> /<br /> SQL> exec pro_leap_year(2010);<br /> 2010 is not a leap year<br /> PL/SQL procedure successfully completed<br /> //<br /> SQL> exec pro_leap_year(2000);<br /> 2000 is a leap year<br /> PL/SQL procedure successfully completed<br /> //<br /> SQL> exec pro_leap_year(2005);<br /> 2005 is not a leap year<br /> PL/SQL procedure successfully completed<br /> //<br /> SQL> exec pro_leap_year(2100);<br /> 2100 is not a leap year<br /> PL/SQL procedure successfully completed<br /> //<br /> //我们也可以用一条select语句来判断：<br /> SQL> select case<br /> 2 when to_char(last_day(to_date(&year||'02','yyyymm')),'dd')='29'<br /> 3 then 'the year you input is a leap year'<br /> 4 else 'the year you input is not a leap year'<br /> 5 end is_leap_year<br /> 6 from dual;<br /> Enter value for year: 2050<br /> old 2: when to_char(last_day(to_date(&year||'02','yyyymm')),'dd')='29'<br /> new 2: when to_char(last_day(to_date(2050||'02','yyyymm')),'dd')='29'<br /> IS_LEAP_YEAR<br /> -------------------------------------<br /> the year you input is not a leap year<br /> //<br /> SQL> /<br /> Enter value for year: 2000<br /> old 2: when to_char(last_day(to_date(&year||'02','yyyymm')),'dd')='29'<br /> new 2: when to_char(last_day(to_date(2000||'02','yyyymm')),'dd')='29'<br /> IS_LEAP_YEAR<br /> ---------------------------------<br /> the year you input is a leap year<br /> //<br /> SQL> /<br /> Enter value for year: 2012<br /> old 2: when to_char(last_day(to_date(&year||'02','yyyymm')),'dd')='29'<br /> new 2: when to_char(last_day(to_date(2012||'02','yyyymm')),'dd')='29'<br /> IS_LEAP_YEAR<br /> ---------------------------------<br /> the year you input is a leap year<br /> //<br /> SQL> /<br /> Enter value for year: 1998<br /> old 2: when to_char(last_day(to_date(&year||'02','yyyymm')),'dd')='29'<br /> new 2: when to_char(last_day(to_date(1998||'02','yyyymm')),'dd')='29'<br /> IS_LEAP_YEAR<br /> -------------------------------------<br /> the year you input is not a leap year<br /> // 

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