我有mysql DB。
我正在运行以下查询。
SELECT cluster,
infra_properties.property_name property,
count(*)
FROM raw_alerts,
infra_properties
WHERE infra_properties.parent_group = raw_alerts.cluster
AND cluster = 'abuse-content'
AND infra_properties.property_name = 'BigBro'
AND timestamp BETWEEN '2012-12-24 00:00:00' AND '2012-12-24 23:59:59'
GROUP BY cluster;
我得到输出为null但我的要求是得到count = 0。如下所述。
+---------------+----------+----------+
| cluster | property | count(*) |
+---------------+----------+----------+
| abuse-content | BigBro | 0 |
+---------------+----------+----------+
1 row in set (0.30 sec)
答案 0 :(得分:0)
如果2个表上没有匹配的记录,则不会返回任何行。
您可能需要做的是拥有一个包含集群和属性列的额外表,然后执行以下操作: -
SELECT a.cluster, a.property, count(c.id)
FROM SomeExtraTable a
LEFT OUTER JOIN raw_alerts b ON a.cluster = b.cluster AND AND b.cluster = 'abuse-content'
LEFT OUTER JOIN infra_properties c
ON a.property = c.property
AND c.parent_group = b.cluster
AND c.property_name = 'BigBro'
AND c.timestamp BETWEEN '2012-12-24 00:00:00' AND '2012-12-24 23:59:59'
GROUP BY a.cluster, a.property
(我只猜测时间戳列在哪个表上)