如何使用UNION添加两个不同查询的结果

Question

I have these two queries:

SELECT SUM(H) FROM stats_2017
UNION
SELECT SUM(H) FROM my_career_stats;

The first query gives a result of 70 and the second gives the result of 713. I want the sum of 70 and 713 but have not been able to get it. Do you have any suggestions?

Answer 1

SELECT sum(a)
FROM (
  SELECT sum(h) as a FROM stats_2017
  UNION SELECT sum(h) as a FROM my_career_stats) as tmptbl

Explain:

You do your two queryes inside of the from of another select. With that, you can sum both results.

Answer 2

You got two rows already. Now sum them:

SELECT sum(sum_) as total FROM 
  (
    SELECT SUM(H) as sum_ FROM stats_2017 
    UNION 
    SELECT SUM(H) as sum_ FROM my_career_stats
  ) sum_table

Answer 3

Your union query would end up giving you two records, one record per sum. Because you are selecting only a single value, you can omit the GROUP BY clause. I used the SUM() function and added it to a similar statement using an inline subquery.

SELECT SUM(H) + (SELECT SUM(H) FROM my_career_stats)
FROM stats_2017