我正在使用oracle编写一个查询来获取每年的每个类型的电影号码，但我遇到两个问题： 如果我想添加一个名为2015年之前的新专栏，该专栏将每种类型的2015年之前制作的电影数量相加，我该怎么办？我尝试过解码，但它似乎只能识别像2015这样的实际单词，而不是表达<2015 在下面的类型中，有许多类型的经典科幻小说，如果我想将所有经典类型组合在一起，而不是经典，经典戏剧，经典浪漫，经典战争。我怎样才能做到这一点？

SQL> select decode(genre,null,'Year Total',genre) genre, 2 sum(decode (year, 2015, 1, 0)) Year2015, 3 sum(decode (year, 2016, 1, 0)) Year2016, 4 sum(decode (year, 2017, 1, 0)) Year2017 5 from film 6 group by rollup(genre); GENRE YEAR2015 YEAR2016 YEAR2017 ------------------------- ---------- ---------- ---------- Action and Adventure 1 1 0 Children and Family 0 1 1 Classic 0 0 0 Classic, Drama 0 0 0 Classic, Romance 0 0 0 Classic, War 0 0 0 Comedy 0 0 0 Documentary 0 0 0 Fantasy 1 0 0 Sci-Fi 0 2 1 TV Drama 2 0 1 TV Sci-Fi 0 0 0 Thriller 0 0 0 War 0 0 0 Year Total 4 4 3

这里编辑的是样本数据：

INSERT INTO film VALUES ('11W', 'Wide Screen', 'Gone with the Wind', 1939, 2, null, 233, 'Romance');

INSERT INTO film VALUES ('12F', 'Full Screen', 'The Longest Day', 1962, 1, null, 178, 'War');

INSERT INTO film VALUES ('13F', 'Full Screen', 'Roman Holiday', 1953, 1, 'NR', 118, 'Classic');

INSERT INTO film VALUES ('14F', 'Full Screen', 'Sabrina', 1954, 1,'NR', 113, 'Classic');

INSERT INTO film VALUES ('15W', 'Wide Screen', 'Breakfast at Tiffany', 1961, 1, 'NR', 115, 'Classic');

INSERT INTO film VALUES ('16W', 'Wide Screen', 'My Fair Lady', 1964, 1, 'G', 172, NULL);

INSERT INTO film VALUES ('17F', 'Full Screen', 'The Heart is a Lonely Hunter', 1968, 1, null, 123, 'Drama');

INSERT INTO film VALUES ('23W', 'Full Screen', 'Titanic: The Complete Story', 1994, 2,'NR', 300, 'Documentary');

INSERT INTO film VALUES ('24F', 'Full Screen', 'Rush Hour', 1998, 1, 'PG-13', 98, 'Comedy');

INSERT INTO film VALUES ('28W', 'Wide Screen', 'Pearl Harbor', 2001, 1, 'PG-13', 183, 'War');

INSERT INTO film VALUES ('31W', 'Wide Screen', 'Avatar', 2010, 3,'PG-13', 162,'Sci-Fi');

INSERT INTO film VALUES ('38W', 'Wide Screen', 'Star Wars: The Force Awakens', 2016, 3,'PG-13', 136,'Sci-Fi');

INSERT INTO film VALUES ('40W', 'Wide Screen', 'Harry Potter and the Deathly Hollows: Part I', 2011, 1, 'PG-13', 146, 'Fantasy');

INSERT INTO film VALUES ('41W', 'Multiple Formats', 'Transformers: Age of Extinction', 2014, 1,'PG-13', 164,'Action and Adventure');

INSERT INTO film VALUES ('42F', 'Wide Screen', 'Horrible Bosses', 2011, 1, 'R', 98, 'Comedy');

INSERT INTO film VALUES ('43W', 'Wide Screen', 'Rogue One: A Star Wars Story', 2017, 3,'PG-13', 133,'Sci-Fi');

INSERT INTO film VALUES ('44W', 'Wide Screen', 'The Prince of Persia: The Sands of Time', 2010, 1,'PG-13', 116, 'Action and Adventure');

INSERT INTO film VALUES ('45W', 'Wide Screen', 'Clash of the Titans', 2010, 1,'PG-13', 106, 'Action and Adventure');

INSERT INTO film VALUES ('46W', 'Wide Screen', 'Skyfall', 2012, 1, 'PG-13', 143, 'Action and Adventure');

INSERT INTO film VALUES ('47W', 'Wide Screen', 'Hugo', 2012, 1,'PG', 126,'Children and Family');

INSERT INTO film VALUES ('48W', 'Wide Screen', 'Brave', 2012, 1, 'PG', 93, 'Children and Family');

INSERT INTO film VALUES ('49W', 'Wide Screen', 'Zootopia', 2016, 1,'PG', 108,'Children and Family');

INSERT INTO film VALUES ('50W', 'Wide Screen', 'Star Trek', 2010, 1, 'PG-13', 127, 'Sci-Fi');

INSERT INTO film VALUES ('60W', 'Wide Screen', 'Harry Potter and the Deathly Hollows: Part II', 2012, 1, 'PG-13', 130, 'Fantasy');

INSERT INTO film VALUES ('61W', 'Multiple Formats', 'Guardians of the Galaxy', 2014, 1, 'PG-13', 121, 'Sci-Fi');

INSERT INTO film VALUES ('62W', 'Wide Screen', 'Alphas: Season 1', 2012, 3,'NR', 497,'TV Sci-Fi');

INSERT INTO film VALUES ('63W', 'Wide Screen', 'The Dark Knight Rises', 2012, 1, 'PG-13', 165, 'Action and Adventure');

INSERT INTO film VALUES ('64W', 'Wide Screen', 'The Avengers', 2012, 1, 'PG-13', 143, 'Action and Adventure');

INSERT INTO film VALUES ('65W', 'Wide Screen', 'Wrath of the Titans', 2012, 1, 'PG-13', 99, 'Action and Adventure');

INSERT INTO film VALUES ('66W', 'Multiple Formats', 'Scorpion: Season 1', 2015, 6,'NR', 916,'TV Drama');

INSERT INTO film VALUES ('67W', 'Wide Screen', 'Spectre', 2016, 1, 'PG-13', 150, 'Action and Adventure');

INSERT INTO film VALUES ('68W', 'Wide Screen', 'Alphas: Season 2', 2013, 3,'NR', 562,'TV Sci-Fi');

INSERT INTO film VALUES ('71W', 'Wide Screen', 'The Croods', 2013, 1, 'PG', 96, 'Children and Family');

INSERT INTO film VALUES ('72W', 'Wide Screen', 'Moana', 2017, 1,'PG', 107,'Children and Family');

INSERT INTO film VALUES ('73W', 'Wide Screen', 'A Good Day to Die Hard', 2013, 1, 'R', 97, 'Thriller');

INSERT INTO film VALUES ('74W', 'Wide Screen', 'Star Trek: Into Darkness', 2013, 1, 'PG-13', 132, 'Sci-Fi');

INSERT INTO film VALUES ('80W','Wide Screen', 'The Hunger Game: Catching Fire', 2014, 1,'PG-13', 146,'Sci-Fi');

INSERT INTO film VALUES ('81W','Wide Screen', 'The Hobbit: The Desolation of Smaug', 2014, 2,'PG-13', 161,'Fantasy');

INSERT INTO film VALUES ('82W','Wide Screen', 'The Hobbit: The Battle of the Five Armies', 2015, 2,'PG-13', 144,'Fantasy');

INSERT INTO film VALUES ('83W','Wide Screen', 'Lucy', 2015, 2,'R', 90,'Action and Adventure');

INSERT INTO film VALUES ('84M','Multiple Formats', 'Star Trek Beyond',2016,2,'PG-13',122,'Sci-Fi');

1

投票

您可以使用sign()(代表数学中的signum)函数来派生您想要的列：

sum(decode (sign(year - 2015), -1 , 1, 0)) as Before2015

你可以使用这个查询

select decode(substr(genre,1,7),'Classic','Classic',genre),

sum(decode (sign(year - 2015), -1 , 1, 0)) as Before2015,

sum(decode (year, 2015, 1, 0)) Year2015,

sum(decode (year, 2016, 1, 0)) Year2016,

sum(decode (year, 2017, 1, 0)) Year2017

from film

group by rollup(decode(substr(genre,1,7),'Classic','Classic',genre))

结合所有Classic类型电影。