[英]sql coalesce not working with group by mysql
我有一張像這樣的桌子:
+----+------+-------+ | 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 | +----+------+-------+
當使用合並時:
select id,name,coalesce(value) from hey group by name;
output 是:
+----+------+-------+ | id | name | value | +----+------+-------+ | 1 | bob | k | | 2 | kate | NULL | +----+------+-------+
如何實現所需的 output? 請
您想要聚合,但您需要正確構造它:
select min(id) as id, name, max(value)
from hey
group by name;
“正確”意味着所有非聚合列都應該是參數函數的 arguments ,例如max()
或min()
。
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