崩潰數據

Question

在我的數據庫中，我有數據列表

名稱值

a/b/c  1 
a/b/c/d 1 
a/b/c/d/e 1 
b/b/c  1 
b/b/c/d 2 
c/c/d  3 
c/c/d/e 4 
d/d  5 

如果我設置最長3我想

a/b/c 3 
b/b/c 3 
c/c/d 7 
d/d 5 

我該怎麼辦這個？

CREATE TABLE dataTable (
ID       BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY, 
Name      VARCHAR(255), 
Value      INT 
) ENGINE=InnoDB; 


INSERT INTO dataTable (Name, Value) VALUES ("a/b/c", 1), ("a/b/c/d", 1), ("a/b/c/d/e", 1), ("b/b/c", 1), ("b/b/c/d", 1), ("c/c/d", 1), ("c/c/d/e", 1), ("d/d", 1); 

Answer 1

SELECT LEFT(Name, 5) AS Name, SUM(Value) as TotalValue 
    FROM dataTable 
    GROUP BY LEFT(Name, 5) 

很顯然，我硬編碼在我的例子中，5，但你可以做這樣一個變量（2 * MAXLEN-1）。

Answer 2

select name, 
sum(value) as cnt 
from 
dataTable 
group by substring_index(name,'/',3)