Question

字段版本可以为null但我也需要对这些行进行计数我试图这样做：IFNULL（COUNT（版本），1），但不工作

select MIN(id) as id, version, IFNULL(COUNT(version), 1) as total
from hlrlookup.hlrlookup
WHERE create_timestamp > '2015-02-01 05:00:00' and create_timestamp < '2016-04-28 06:00:00'
group by version;

帮助

Answer 1

alpha:0.7永远不会返回COUNT() - 而是返回NULL。如果要计算所有行数，请使用0：

COUNT(*)

编辑：

我应该注意，表达你想要做的逻辑的正确方法是：

select MIN(id) as id, version, COUNT(*) as total
from hlrlookup.hlrlookup
WHERE create_timestamp > '2015-02-01 05:00:00' and
      create_timestamp < '2016-04-28 06:00:00'
GROUP BY version;

Answer 2

您在分组声明中有version。您只需对每个版本的行进行求和：

select MIN(id) as id, version, SUM(1) as total
from hlrlookup.hlrlookup
WHERE create_timestamp > '2015-02-01 05:00:00' and create_timestamp < '2016-04-28 06:00:00'
group by version;

mysql如何COUNT（）nullleble字段+ IFNULL

2 个答案: