SQL - 将两列一起计数

Question

我正在尝试将多列计为一列。例如：

Table 1（书籍）：

ID	BookName	Genre	SubGenre
1	Name1	1	3
2	Name2	2	1
3	Name3	4	2

Table 2（流派）：

ID	Genre
1	Horror
2	Drama
3	Romance
4	Sci-Fi

我希望能够将流派和子流派算作一个来创建 table 的：

结果：

Genre	Count
Horror	2
Drama	2
Romance	1
Sci-Fi	1

任何帮助将不胜感激。谢谢

Answer 1

尝试以下查询-

SELECT t.Genre, Sum(t.cg) AS Count
FROM (

SELECT t2.Genre, Count(t1.Genre) AS cg
FROM Table2 as t2 LEFT JOIN Table1 as t1 ON t2.ID = t1.Genre
GROUP BY t2.Genre

UNION ALL 

SELECT t2.Genre, Count(t1.SubGenre) AS cg
FROM Table2 as t2 LEFT JOIN Table1 as t1 ON t2.ID = t1.SubGenre
GROUP BY t2.Genre

) as t GROUP BY t.Genre;

SQL - 将两列一起计数

SQL - Count two columns together

ms-access