Question

我正在使用Postgresql，我创建了两个返回结果的子查询，如下所示：

firm_id      type_1      fee_1
   1           2          100
   2           4          300
   5           1          100

firm_id      type_2      fee_2
   1           3          200
   2           3          200
   3           2          150
   4           5          300

我想得到一个结果：

firm_id      type_1     type_2    total_fee
   1           2          3         300
   2           4          3         500
   3           0          2         150
   4           0          5         300
   5           1          0         100

任何帮助表示赞赏！

Answer 1

使用FULL JOIN和coalesce()：

with q1(firm_id, type_1, fee_1) as (
    values
    (1, 2, 100),
    (2, 4, 300),
    (5, 1, 100)),
q2 (firm_id, type_2, fee_2) as (
    values
    (1, 3, 200),
    (2, 3, 200),
    (3, 2, 150),
    (4, 5, 300))

select 
    firm_id, 
    coalesce(type_1, 0) type_1, 
    coalesce(type_2, 0) type_2, 
    coalesce(fee_1, 0)+ coalesce(fee_2, 0) total_fee
from q1
full join q2
using (firm_id);

 firm_id | type_1 | type_2 | total_fee 
---------+--------+--------+-----------
       1 |      2 |      3 |       300
       2 |      4 |      3 |       500
       3 |      0 |      2 |       150
       4 |      0 |      5 |       300
       5 |      1 |      0 |       100
(5 rows)

Answer 2

SELECT firm_id
    ,coalesce(t.type_1, 0) type_1
    ,coalesce(b.type_1, 0) type_2
    ,coalesce(t.fee_1, 0) + coalesce(b.fee_1, 0) total_fee
FROM (
    SELECT *   --Your first select query
    FROM tablea
    ) t
FULL JOIN (
    SELECT *   --Your second select query
    FROM tableb
    ) b using (firm_id)

FULL JOIN：结合左外连接和右外连接的结果。连接表将包含两个表中的所有记录，并为任何一方的缺失匹配填写NULL。

COALESCE函数返回其第一个非null的参数。仅当所有参数都为null时才返回Null。当检索数据用于显示时，它通常用于替换默认值为空值

Answer 3

SELECT coalesce( t1."firm_id", t2."firm_id" ) as firm_id,
       coalesce( t1."type_1", 0 ) as type_1,
       coalesce( t2."type_2", 0 ) as type_2,
       coalesce( t1."fee_1", 0 ) 
       +
       coalesce( t2."fee_2", 0 ) as total_fee
FROM table1 t1
FULL JOIN table2 t2
ON t1."firm_id" = t2."firm_id"

其中table1和table2必须由子查询替换

看演示：http://sqlfiddle.com/#!15/6d391/2

Answer 4

select coalesce(sq1.firm_id, sq2.firm_id) as firm_id, coalesce(type_1, 0), coalesce(type_2, 0), coalesce(fee_1, 0)+coalesce(fee_2, 0) as total_fee 
from <subquery1> as sq1 
outer join <subquery1> as sq1 
on sq1.firm_id=sq2.firm_id

Answer 5

如果您有两个子查询，例如a和b，它们为您设置A并设置B，那么您要查找的是完全连接A x B，其中完整连接中的至少一个firm_id不为空，计算列total_fee = fee_1 + fee_2。

我对postgresql语法并不熟悉，但它应该像

select 
    -- get rid of the columns you don't want
    a.firm_id, a.type_1, a.type_2, a.fee_1, 
    b.firm_id, b.type_1, b.type_2, b.fee_2, 
    a.fee_1 + b.fee_2 as total_fee
from ( subquery_1 here ) as a
full join ( subquery_2 here) as b 
on
    b.firm_id = a.firm_id and 
    b.type_1 <> a.type_1 
where 
    a.firm_id is not null or b.firm_id is not null

合并两个子查询Postgresql的结果

5 个答案: