如何在 postgreSQL 中将行展平为列

Question

使用 postgresql 9.3 我有一个 table 显示一年内颁发的个人许可证如下：

permit_typ| zipcode| address| name
-------------+------+------+-----
CONSTRUCTION      | 20004 | 124 fake streeet | billy joe
SUPPLEMENTAL      | 20005 | 124 fake streeet  | james oswald
POST CARD         | 20005 | 124 fake streeet  | who cares
HOME OCCUPATION   | 20007 | 124 fake streeet  | who cares
SHOP DRAWING      | 20009 | 124 fake streeet  | who cares

我想把它弄平，让它看起来像

CONSTRUCTION | SUPPLEMENTAL | POST CARD| HOME OCCUPATION | SHOP DRAWING | zipcode
-------------+--------------+-----------+----------------+--------------+--------
1            |  2           | 3         |   5            |   6          |  20004 
1            |  2           | 3         |   5            |   6          |  20005
1            |  2           | 3         |   5            |   6          |  20006
1            |  2           | 3         |   5            |   6          |  20007
1            |  2           | 3         |   5            |   6          |  20008

一直在尝试使用交叉表，但它有点超出我生锈的 SQL 经验。大家有什么想法

Answer 1

我通常使用条件聚合来处理此类查询。在 Postgres 中，您可以：

select zipcode,
       sum( (permit_typ = 'CONSTRUCTION')::int) as Construction,
       sum( (permit_typ = 'SUPPLEMENTAL')::int) as SUPPLEMENTAL,
       . . .
from t
group by zipcode;