PostgreSQL 9.3：交叉表查询

Question

我有一个表称为测试，它具有四列，如下所示。

create table testing 
(
cola varchar(10), 
colb varchar(10), 
colc varchar(10), 
cold varchar(10) 
); 

插入一些行：

insert into testing values('A1','City1','X1','Z1'), 
       ('A2','City2','X2','Z2'), 
       ('A3','City3','X3','Z3'), 
       ('A4','City4','X4','Z4'); 

预期结果：我想表明它看起来像如下所示的结果：

cola City1 City2 City3 City4 colc cold 
-------------------------------------------- 
A1  1  0  0  0  X1 Z1 
A2  0  1  0  0  X2 Z2 
A3  0  0  1  0  X3 Z3 
A4  0  0  0  1  X4 Z4   

我尝试：

我试着用下面的脚本，但得到一个错误。

select * from crosstab 
(
'select cola,colb,count(colb),colc,cold from testing group by 1,2,4,5 order by 1,2,4,5', 
'select distinct colb from testing' 
) 
as t 
(
    cola varchar(10),City1 integer,City2 integer,City3 integer,City4 integer,colc varchar(10),cold varchar(10) 
); 

错误详细信息：

ERROR: invalid input syntax for integer: "City1" 

Answer 1

也许这是你想要的吗？

select x1.*, x2.colc, x2.cold from crosstab 
($$select x1.cola, x2.colb, 
    CASE WHEN x1.colb = x2.colb THEN 1 ELSE 0 END 
    FROM testing x1 CROSS JOIN testing x2 
    $$ 
) AS x1(cola VARCHAR(10), City1 INT, City2 INT, City3 INT, City4 INT) 
LEFT JOIN testing x2 ON x1.cola = x2.cola; 

结果：

cola | city1 | city2 | city3 | city4 | colc | cold 
------+-------+-------+-------+-------+------+------ 
A1 |  1 |  0 |  0 |  0 | X1 | Z1 
A2 |  0 |  1 |  0 |  0 | X2 | Z2 
A3 |  0 |  0 |  1 |  0 | X3 | Z3 
A4 |  0 |  0 |  0 |  1 | X4 | Z4