比较两个不同 SQL 表的计数

Question

我有两个表 A 和 B，我正在尝试比较它们的数量

SELECT COUNT(*) FROM table_a WHERE day = '2018-09-27' AS A,
COUNT(*) FROM table_b WHERE day = '2018-09-27' AS B;

作为中间步骤执行此操作时出现错误。我的目标是获得

的输出

day      table_a    table_b    difference    %difference
9/25/18    1            1             0          0
9/24/18    2            1             1          50%

Answer 1

这样做的简单方法

select 
    A,
    B,
    A-B as difference
From
(
select
(SELECT COUNT(*) FROM table_a WHERE day = '2018-09-27') as A,
(select COUNT(*) FROM table_b WHERE day = '2018-09-27') as B
) Res

Answer 2

试试这个：

SELECT COALESCE(a.day, b.day) AS day
     , count_a
     , count_b
     , count_a - count_b AS difference
  FROM ( SELECT day, count(*) AS count_a FROM table_a GROUP BY day ) a
  FULL JOIN ( SELECT day, count(*) AS count_b FROM table_b GROUP BY day ) b
       ON b.day = a.day

比较两个不同 SQL 表的计数

Comparing count of two different SQL tables

sql

presto