Question

我尝试以案例的形式告诉我每个位置的数量。我只是无法获得所需结果的格式。

我有一张简单的桌子：

create table rot (
            code int(10) primary key,
            PN varchar(10) not null,
            Qty int(10) not null,
                Loc varchar(10));

insert into rot values (1,'T1',5,'a');
insert into rot values (2,'A1',6,'b');
insert into rot values (3,'J1',1,'c');
insert into rot values (4,'A2',2,'a');
insert into rot values (5,'J2',1,'b');
insert into rot values (6,'A3',2,'c');
insert into rot values (7,'J3',3,'d');
insert into rot values (8,'T1',3,'e');
insert into rot values (9,'A1',3,'a');
insert into rot values (10,'J2',3,'c');
insert into rot values (11,'J2',3,'d');
insert into rot values (12,'A1',1,'c');
insert into rot values (13,'J2',0,'e');

我想将其转换为以下格式：

PN  a   b   c   d   e
A1  3   6   1       
A2  2               
A3          2       
J1          1       
J2      1       3   0
J3              3   
T1  5               3

在以下情况下，我使用以下情况：

SELECT 
   PN
 ,(CASE WHEN Loc = 'a'  THEN Qty END) AS 'a'
 ,(CASE WHEN Loc = 'b'  THEN Qty END) AS 'b'
 ,(CASE WHEN Loc = 'c'  THEN Qty END) AS 'c'
 ,(CASE WHEN Loc = 'd'  THEN Qty END) AS 'd'
 ,(CASE WHEN Loc = 'e'  THEN Qty END) AS 'e'


FROM rot

GROUP BY PN

当我改用,SUM(CASE WHEN Loc = 'a' THEN Qty END) AS 'a'时，结果相同。

Answer 1

使用汇总函数max以便根据条件按组选择值

SELECT 
   PN
 ,MAX(CASE WHEN Loc = 'a'  THEN Qty END) AS 'a'
 ,MAX(CASE WHEN Loc = 'b'  THEN Qty END) AS 'b'
 ,MAX(CASE WHEN Loc = 'c'  THEN Qty END) AS 'c'
 ,MAX(CASE WHEN Loc = 'd'  THEN Qty END) AS 'd'
 ,MAX(CASE WHEN Loc = 'e'  THEN Qty END) AS 'e'
FROM rot
GROUP BY PN

Demo

MySQL案例何时总结表

1 个答案: