如何在mysql中进行数据透视查询？

Question

我有一个表criteria其结构如下：

+----------+------+-------+
| criteria | user | total |
+----------+------+-------+
| xxxxxxxx | xx   | xxx   |
+----------+------+-------+

我在创建查询时遇到问题。 我想从单个表进行数据透视查询，并且我有以下数据：

+----------+------+-------+
| criteria | user | total |
+----------+------+-------+
|    F1    |  A1  |  17   |
|    F2    |  A1  |  9    |
|    F3    |  A1  |  6    |
|    F4    |  A1  |  4    |
|    F1    |  A2  |  19   |
|    F2    |  A2  |  6    |
|    F3    |  A2  |  2    |
|    F4    |  A2  |  8    |
+----------+------+-------+

我想使查询枢轴是这样的：

+----------+------+-------+------+-------+
| criteria | user | total | user | total |
+----------+------+-------+------+-------+
|    F1    |  A1  |  17   |  A2  |  19   |
|    F2    |  A1  |  9    |  A2  |  6    |
|    F3    |  A1  |  6    |  A2  |  2    |
|    F4    |  A1  |  4    |  A2  |  8    |
+----------+------+-------+------+-------+    

有人可以帮我写一个查询以获得上述结果吗？

Answer 1

您的问题似乎可以通过自连接而不是枢轴来很好地解决。 您可以使用“ criteria列将criteria表自身JOIN在一起：

SELECT c1.criteria AS criteria, c1.user AS user, c1.total AS total,
    c2.user AS user, c2.total AS total
FROM criteria c1 INNER JOIN criteria c2
ON c1.criteria = c2.criteria
WHERE c1.user < c2.user