我抓住机会学习sql。我有一个名为book的基本表。我已经看到了这个场景：显示书籍类别和数量
平均价格大于15的书籍的每本书类别的书籍
美元。我的查询无效。我如何计算每本书type并获得平均价格以查看它是否大于15？
查询
SELECT type FROM books WHERE COUNT(DISTINCT type) * SUM(price) > 15;
表架构
Select * From Book;
BOOK TITLE PUB TYP PRICE P
---- ---------------------------------------- --- --- ---------- -
0180 A Deepness in the Sky TB SFI 7.19 Y
0189 Magic Terror FA HOR 7.99 Y
0200 The Stranger VB FIC 8 Y
0378 Venice SS ART 24.5 N
079X Second Wind PU MYS 24.95 N
0808 The Edge JP MYS 6.99 Y
1351 Dreamcatcher: A Novel SC HOR 19.6 N
1382 Treasure Chests TA ART 24.46 N
138X Beloved PL FIC 12.95 Y
2226 Harry Potter and the Prisoner of Azkaban ST SFI 13.96 N
2281 Van Gogh and Gauguin WP ART 21 N
2766 Of Mice and Men PE FIC 6.95 Y
2908 Electric Light FS POE 14 N
3350 Group: Six People in Search of a Life BP PSY 10.4 Y
3743 Nine Stories LB FIC 5.99 Y
3906 The Soul of a New Machine BY SCI 11.16 Y
5163 Travels with Charley PE TRA 7.95 Y
5790 Catch-22 SC FIC 12 Y
6128 Jazz PL FIC 12.95 Y
6328 Band of Brothers TO HIS 9.6 Y
669X A Guide to SQL CT CMP 37.95 Y
6908 Franny and Zooey LB FIC 5.99 Y
7405 East of Eden PE FIC 12.95 Y
7443 Harry Potter and the Goblet of Fire ST SFI 18.16 N
7559 The Fall VB FIC 8 Y
8092 Godel, Escher, Bach BA PHI 14 Y
8720 When Rabbit Howls JP PSY 6.29 Y
9611 Black House RH HOR 18.81 N
9627 Song of Solomon PL FIC 14 Y
9701 The Grapes of Wrath PE FIC 13 Y
9882 Slay Ride JP MYS 6.99 Y
9883 The Catcher in the Rye LB FIC 5.99 Y
9931 To Kill a Mockingbird HC FIC 18 N
答案 0 :(得分：0)
如果要在过滤器中包含聚合，则应GROUP BY，然后使用HAVING子句。
SELECT type FROM books
GROUP BY type
HAVING COUNT(*) * SUM(price) > 15;