我在单个表中的列lbb_diag_value中有两条消息('usb_port_reset','onewire_cable')。
我使用的两列是:created_at(带有时间戳),lbb_diag_value
问题:我想将one_wire_cable与所有连续的usb_port_reset消息相关联,直到在表中找到另一个one_wire_cable。
例如:
Created_at lbb_diag_value
1 PM onewire_cable
1:15 PM usb_port_reset
3:00 Pm usb_port_reset
12Pm onewire_cable
Some Time usb_port_reset
当前解决方案:我正在使用滞后函数和左连接,如果我没有连续的USB端口重置消息,这可以正常工作。
以下是我的代码:
WITH CTE
AS (
SELECT e2.identifier
,e2.created_at
,e2.model
,e2.sw_pkg_version
,e2.type
,e2.lbb_diag_value
,e2.lbb_diag_type
FROM (
SELECT e1.identifier
,e1.created_at
,e1.model
,e1.sw_pkg_version
,e1.lbb_diag_type
,e1.lbb_diag_value
,e1.type
FROM eld_messages e1
WHERE e1.type = 'lbb_diag'
AND e1.lbb_diag_type = 'usb_port_reset'
AND { % condition created_filter % } e1.created_at { % endcondition % }
) e2
)
,onewire
AS (
SELECT e2.identifier
,e2.lbb_diag_value
,e2.created_at
,e2.type
,e2.lbb_diag_type
,e2.prev_lbb_diag_type
,e2.prev_created_at
,e2.prev_lbb_diag_value
,e2.model
,e2.sw_pkg_version
,e2.seqnum
FROM (
SELECT e1.identifier
,e1.created_at
,e1.lbb_diag_value
,e1.type
,e1.lbb_diag_type
,e1.event_id
,e1.model
,e1.sw_pkg_version
,LAG(e1.lbb_diag_type) OVER (
PARTITION BY e1.identifier ORDER BY e1.created_at
,e1.event_id DESC
) AS prev_lbb_diag_type
,LAG(e1.created_at) OVER (
PARTITION BY e1.identifier ORDER BY e1.created_at
,e1.event_id DESC
) AS prev_created_at
,LAG(e1.lbb_diag_value) OVER (
PARTITION BY e1.identifier ORDER BY e1.created_at
,e1.event_id
) AS prev_lbb_diag_value
,row_number() OVER (
PARTITION BY e1.lbb_diag_type ORDER BY e1.created_at
,e1.event_id DESC
) seqnum
FROM eld_messages e1
WHERE e1.type = 'lbb_diag'
AND e1.lbb_diag_type IN (
'onewire_cable'
,'usb_port_reset'
)
AND { % condition created_filter % } e1.created_at { % endcondition % }
ORDER BY e1.identifier
,e1.created_at
) e2
WHERE (
e2.lbb_diag_type = 'usb_port_reset'
AND e2.prev_lbb_diag_type = 'onewire_cable'
)
OR (
CASE
WHEN e2.lbb_diag_type = 'usb_port_reset'
AND e2.prev_lbb_diag_type = 'usb_port_reset'
THEN e2.seqnum = 1
END
)
)
SELECT cte.identifier
,cte.created_at
,cte.model
,cte.sw_pkg_version
,cte.type
,cte.lbb_diag_type
,cte.lbb_diag_value
,onewire.prev_lbb_diag_value AS onewire_lbb_diag_value
,onewire.prev_created_at AS onewire_created_at
FROM cte
LEFT JOIN onewire ON cte.identifier = onewire.identifier
AND cte.created_at = onewire.created_at;
是否可以使用延迟嵌套子选择并过滤掉lbb_diag_value没有变化的记录?我没有尝试理解那个巨大查询的整个上下文,如果你需要其他记录,但是滞后可以是检测边界的好方法,看起来就像你需要的那样。
FROM (
SELECT * FROM (
SELECT e1.identifier ,e1.created_at ,e1.lbb_diag_value ,e1.type ,e1.lbb_diag_type ,e1.event_id
,e1.model ,e1.sw_pkg_version
,LAG(e1.lbb_diag_type) OVER (PARTITION BY e1.identifier ORDER BY e1.created_at ,e1.event_id DESC) AS prev_lbb_diag_type
,LAG(e1.created_at) OVER ( PARTITION BY e1.identifier ORDER BY e1.created_at ,e1.event_id DESC) AS prev_created_at
,LAG(e1.lbb_diag_value) OVER ( PARTITION BY e1.identifier ORDER BY e1.created_at ,e1.event_id) AS prev_lbb_diag_value
,row_number() OVER (PARTITION BY e1.lbb_diag_type ORDER BY e1.created_at ,e1.event_id DESC) seqnum
FROM eld_messages e1
WHERE e1.type = 'lbb_diag' AND e1.lbb_diag_type IN ('onewire_cable' ,'usb_port_reset')
AND { % condition created_filter % } e1.created_at { % endcondition % }
ORDER BY e1.identifier, e1.created_at
) t
WHERE lbb_diag_value != prev_lbb_diag_value
) e2
如果您需要所有记录,您可以将其转换为带有连接的两个子选择(您已离开的选择连接到检测转换的选择),其中转换(lbb_diag_value!= prev_lbb_diag_value)最终作为指示记录的新列从一个值转换到另一个值。
然后识别'onewire_cable'将是这样的:
select * from (
...join...
) j where j.flip = 1 and j.lbb_diag_value = 'onewire_cable'