Question

我有两个表，其中公共列是位置，我正在寻找两个表中的位置计数并显示组合计数。

    Table-1 
+-------------+
|  Location   |
+-------------+
|    USA      |
|   INDIA     |
|    UK       |
|   INDIA     |
+-------------+

   Table -2
+-------------+
|  Location   |
+-------------+
|   INDIA     |
|   INDIA     |
|    USA      |
+-------------+

此处表一的计数是：

+-------------+--------+
|  Location   | COUNT  |
+-------------+--------+
|    USA      |   1    |
|   INDIA     |   2    |
|    UK       |   1    |
+-------------+--------+

表2中的计数是：

+-------------+--------+
|  Location   | COUNT  |
+-------------+--------+
|    USA      |   1    |
|   INDIA     |   2    |
+-------------+--------+

这个计数到了：

SELECT Location, COUNT(*) AS COUNT FROM Table-1 GROUP BY Location;
SELECT Location, COUNT(*) AS COUNT FROM Table-2 GROUP BY Location;

但我希望两张表中的组合计数看起来像：

+-------------+--------+
|  Location   | COUNT  |
+-------------+--------+
|    USA      |   2    |
|   INDIA     |   4    |
|    UK       |   1    |
+-------------+--------+

提前谢谢。

Answer 1

您可以尝试在两个表之间选择UNION ALL，然后像以前一样使用GROUP BY计算计数：

SELECT t.Location, COUNT(*) AS COUNT
FROM
(
    SELECT Location FROM Table-1
    UNION ALL
    SELECT Location FROM Table-2
) t
GROUP BY t.Location

Answer 2

您可以添加虚拟列，然后添加两列

select tt.Location, SUM(count1+count2) from 
(
SELECT Location, COUNT(*) count1, 0 AS COUNT2 FROM Table-1 GROUP BY Location;
UNION 
SELECT Location, 0 AS COUNT1, COUNT(*) count2 FROM Table-2 GROUP BY Location;
)tt
group by tt.Location

结果，count1是表-1中的总数，count2是表-2中的总数。

mysql从两个表计数并给出组合的字符串数

2 个答案: