在Postgresql的共享日期計數兩個表

Question

我有兩個獨立的客戶表A和B.我試圖計算按日期在同一查詢中創建的客戶A和B.我可以通過Union All獲得正確的數據，但沒有正確分組。

我想要的數據，像這樣：

date,count A created, count B created 
4/15/2015,1,5 

相反的：

date, count 
4/15/2015, 1 
4/15/2015, 5 

感謝幫助！

Answer 1

只要使用一個cte，只需要小心，如果你沒有在每一天的日期。在這種情況下，如果沒有銷售，你需要一個日期表來獲得0。

也儘量不要使用保留字像date作爲FIELDNAMES

with countA as (
    SELECT date, count(*) as CountA 
    from tableA 
    group by date 
), 
countB as (
    SELECT date, count(*) as CountB 
    from tableB 
    group by date 
) 
SELECT A.date, A.CountA, B.CountB 
FROM CountA A 
INNER JOIN CountB B 
    ON A.date = B.date 

與表AllDates解決一天沒有銷售

SELECT T.date, 
     CASE 
      WHEN A.CountA IS NULL THEN 0 
      ELSE A.CountA 
     END as CountA, 
     CASE 
      WHEN B.CountB IS NULL THEN 0 
      ELSE B.CountB 
     END as CountB 

FROM AllDates T 
LEFT JOIN CountA A 
     ON T.date = A.date 
LEFT JOIN CountB B 
     ON T.date = B.date 

Answer 2

select a.dte 
     ,a.count a_created 
     ,b.count b_created 
from 
(select dte,count(*)from table_a group by dte) a 
,(select dte,count(*)from table_b group by dte) b 
where b.dte=a.dte 

SQLFIDDLE DEMO

OR

您可以使用使用PostgreSQL的tablefunc

開始BTY創建CREATE EXTENSION if not exists tablefunc;

，並通過使用crosstab()以下作爲一個例子

create table table_a (dte date,is_created int); 
create table table_b (dte date,is_created int); 

insert into table_a values('2015-10-07',1); 
insert into table_a values('2015-10-07',1); 
insert into table_a values('2015-10-07',1); 
insert into table_a values('2015-10-07',1); 
insert into table_a values('2015-10-07',1); 

insert into table_b values('2015-10-07',2); 

實現這一目標的選擇應該是

SELECT * 
FROM crosstab(
    'select dte,''a_created'' col,count(*) created from table_a group by dte 
    union all 
    select dte, ''b_created'' col,count(*) created from table_b group by dte') 
AS ct("date" DATE, "a_created" BIGINT, "b_created" BIGINT);