如何将多个sql行连接成一行

Question

我有来自查询的输出：

Select hostname,support1,support2 From hostnames where hostname in ('C')

C | NULL |  NULL 
C | NULL |  B 
C | A | NULL  
C | A | B 

如您所见，有NULL | B和A | NULL。 我需要输出：

C | A | B 

（将两行合并为一行） 这该怎么做 ？ 感谢

Answer 1

您可以使用聚合：

Select hostname, max(support1) as support1, max(support2) as support2
From hostnames
where hostname in ('C') 
group by hostname;