Question

我有一个如下数据集：

ID  Cat
1   Large
1   Small
1   Medium
2   Small
2   Medium
3   Large

我想将其转换为：

ID  Small   Medium   Large
1   Small   Medium   Large
2   Small   Medium   NULL
3   NULL    NULL     Large

我尝试了许多不同的方法，但它们似乎不起作用

感谢您的帮助

Answer 1

这是一个奇怪的期望输出，但唉：

SELECT  ID, 
        MIN(CASE WHEN Cat = 'Small' THEN 'Small' END) Small,
        MIN(CASE WHEN Cat = 'Medium' THEN 'Medium' END) Medium,
        MIN(CASE WHEN Cat = 'Large' THEN 'Large' END) Large
FROM YourTable
GROUP BY ID

Answer 2

<强> SQL Fiddle Demo

SELECT *
FROM MyTable
PIVOT(MAX(Cat) FOR Cat IN (Small,Medium,Large) ) p

SQL - 按ID分组并将行转换为列

2 个答案: