[英]sql coalesce not working with group by mysql
我有一张像这样的桌子:
+----+------+-------+ | id | name | value | +----+------+-------+ | 1 | bob | k | | 2 | kate | NULL | | 3 | bob | NULL | | 4 | kate | w | +----+------+-------+
我想要以下 output:
+----+------+-------+ | id | name | value | +----+------+-------+ | 1 | bob | k | | 2 | kate | W | +----+------+-------+
当使用合并时:
select id,name,coalesce(value) from hey group by name;
output 是:
+----+------+-------+ | id | name | value | +----+------+-------+ | 1 | bob | k | | 2 | kate | NULL | +----+------+-------+
如何实现所需的 output? 请
您想要聚合,但您需要正确构造它:
select min(id) as id, name, max(value)
from hey
group by name;
“正确”意味着所有非聚合列都应该是参数函数的 arguments ,例如max()
或min()
。
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