MySql - 仅由具有特定值的列进行分组（无UNION）

Question

给定以下数据;

column a | column b | column c 
________ ________ _______ 
    A  | apple | 1 
    P  | pear  | 3 
    O  | orange | 4 
    A  | apple | 1 
    P  | peach | 2 
    P  | pear  | 3 
    P  | peach | 1 
    A  | apple | 4 

我想选择和只有组（和总和）由苹果。其余列不会被分组，因此以下是输出;

column a | column b | column c 
________ ________ _______ 
    A  | apple | 6 
    P  | pear  | 3 
    O  | orange | 4 
    P  | peach | 2 
    P  | pear  | 3 
    P  | peach | 1 

是上述可能不使用UNION？

Answer 1

，不使用UNION

SELECT tbl.id,tbl.a,tbl.b,tbl.c FROM (
SELECT id,a, 
    CASE WHEN b='apple' THEN @ap:= (@ap+c) ELSE c END as c, 
    CASE WHEN b = (SELECT b FROM fruit WHERE id > frA.id AND b='apple' LIMIT 1) THEN b ELSE CONCAT(' ',b) END as b 
    FROM fruit AS frA, (SELECT @ap:=0) AS apc 
    ) as tbl 
WHERE tbl.b REGEXP '^[ ].*$' 

现场演示：SQL Fiddle