对 SELECT 查询求和

Question

我目前是运行这个 select 查询（比原来的更短）：

SELECT 'website' service, COUNT(*) 
FROM website 
UNION 
SELECT 'vps' service, COUNT(*) 
FROM vps 
UNION 
SELECT 'other' service, 
COUNT(*) 
FROM other;

我得到这个结果：

Result

+---------+----------+
| service | COUNT(*) |
+---------+----------+
| website |        2 |
| vps     |        1 |
| other   |        2 |
+---------+----------+
3 rows in set (0.01 sec)

我想将 COUNT(*) 列中列出的所有结果相加。

预期结果：

+----------+
| COUNT(*) |
+----------+
|        5 |
+----------+
1 rows in set (0.00 sec)

我该怎么做？

谢谢！

Answer 1

根据评论，您应该在外部查询中添加 SUM。

尝试：

SELECT sum(t1.nr_count)
FROM (
      SELECT 'website' service, COUNT(*) as nr_count  FROM website 
      UNION 
      SELECT 'vps' service, COUNT(*)  as nr_count FROM vps 
      UNION 
      SELECT 'other' service, COUNT(*) as nr_count FROM other       
    ) as t1;

对 SELECT 查询求和

Sum a SELECT query

mysql

vb.net