November 21, 2018 at 6:30 am
Hi, I have the following situation:CREATE TABLE #TAB1(
ID INT
,MY_STATE VARCHAR(10)
,EVENT_TS DATETIME
)
INSERT INTO #TAB1(ID, MY_STATE, EVENT_TS)
VALUES (1, 'STATE_1', GETDATE())
,(1, 'STATE_1', DATEADD(DAY,-1, GETDATE()))
,(1, 'STATE_2', DATEADD(DAY,-2, GETDATE()))
,(1, 'STATE_3', DATEADD(DAY,-5, GETDATE()))
,(2, 'STATE_1', NULL)
,(2, 'STATE_2', GETDATE())
what should query do: WHEN STATE_1 has EVENT_TS NOT NULL THAN take its date, otherwise search for STATE_2 and take its date
Expected result:
1 STATE_1 GETDATE()
2 STATE_2 GETDATE()
I'm thinking about partitioning over id and then use case when to check if a state has a date but I can't write anything that works..
November 21, 2018 at 6:51 am
Deleted!
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.
November 21, 2018 at 7:09 am
@thom-a uhm, if you insert also the following line:INSERT INTO #TAB1(ID, MY_STATE, EVENT_TS) VALUES (1, 'STATE_2', DATEADD(DAY,2, GETDATE()))
the solution you suggested returns STATE_2 also for the first id
1 STATE_2 GETDATE()
2 STATE_2 GETDATE()
while I'd like it to return STATE_1
Best
November 21, 2018 at 7:30 am
Data Cruncher - Wednesday, November 21, 2018 7:09 AM@thom-a uhm, if you insert also the following line:INSERT INTO #TAB1(ID, MY_STATE, EVENT_TS) VALUES (1, 'STATE_2', DATEADD(DAY,2, GETDATE()))the solution you suggested returns STATE_2 also for the first id
1 STATE_2 GETDATE()
2 STATE_2 GETDATE()while I'd like it to return STATE_1
Best
Having sample data that explains the full scenario at the start is always helpful. 🙂
Thom~
Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
Larnu.uk
November 21, 2018 at 7:32 am
Data Cruncher - Wednesday, November 21, 2018 7:09 AM@thom-a uhm, if you insert also the following line:INSERT INTO #TAB1(ID, MY_STATE, EVENT_TS) VALUES (1, 'STATE_2', DATEADD(DAY,2, GETDATE()))the solution you suggested returns STATE_2 also for the first id
1 STATE_2 GETDATE()
2 STATE_2 GETDATE()while I'd like it to return STATE_1
Best
Try this:SELECT TOP 1 WITH TIES
ID
, MY_STATE
, EVENT_TS
FROM #TAB1
WHERE NOT (
MY_STATE = 'STATE_1'
AND EVENT_TS IS NULL
)
ORDER BY ROW_NUMBER() OVER (PARTITION BY ID
ORDER BY MY_STATE ASC
);
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.
November 21, 2018 at 7:33 am
Give this one a go:
Thom~
Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
Larnu.uk
November 21, 2018 at 7:53 am
I believe that this will give you what you want. You can use either BINARY or CHAR as the intermediary data type. BINARY is usually simpler, because you don't have to worry about getting the right format for datetimes or left padding numbers to get the sorts to work correctly, HOWEVER dates should be converted to datetime before being converted to binary.
SELECT ID,
CAST(SUBSTRING(MIN(CAST(MY_STATE AS BINARY(10)) + CAST(EVENT_TS AS BINARY(8))), 1, 10) AS VARCHAR(10)),
CAST(SUBSTRING(MIN(CAST(MY_STATE AS BINARY(10)) + CAST(EVENT_TS AS BINARY(8))), 11, 8) AS DATETIME)
FROM #TAB1
GROUP BY ID
Drew
J. Drew Allen
Business Intelligence Analyst
Philadelphia, PA
November 22, 2018 at 2:23 am
I think Phil's solution works better in the case with more than one states but I'd really like to get the most of this example - for me it's so rare to find good instructive examples, like this one. Starting from Thom-A's solution (that I understand less) I'll try to explain the single steps and ask a few questions.
a) query + subquery
SELECT ID, MY_STATE, EVENT_TS
FROM #TAB1 T1
WHERE T1.MY_STATE = 'STATE_1' -- get all 'STATE_1'
OR NOT EXISTS (SELECT 1 -- (return 1 if there is another row with 'STATE_1' and date NOT NULL)
FROM #TAB1 e
WHERE e.ID = T1.ID
AND e.MY_STATE = 'STATE_1'
AND e.EVENT_TS IS NOT NULL)
Here I don't understand why/how the 'OR NOT EXISTS' part works? If there is a STATE_1 with a valid date I read the where condition as follows:"WHERE T1.MY_STATE = 'STATE_1' OR NOT EXISTS 1"
This should return true and therefore return all rows with a valid date and state different than 'STATE_1', right?
b) TOP (n) WITH TIES
Didn't have a clue about this keyword. After a quick trip to MSDN I realize it's used here to get all ROW_NUMBERS() = 1
So inside each ID you order the results by date in descending order and therefore return the state with a most recent date, is that correct?
How could I modify the initial Thom-A's query in case I have an undefined number of states?
November 29, 2018 at 6:32 am
This at first seemed like there just wasn't any good description of the exact rule for choosing a given row.
So I kept reading along, and then found what may be the key. Try this and let me know if it works for
all cases:CREATE TABLE #TAB1 (
ID int,
MY_STATE varchar(10),
EVENT_TS datetime
);
INSERT INTO #TAB1 (ID, MY_STATE, EVENT_TS)
VALUES (1, 'STATE_1', GETDATE()),
(1, 'STATE_1', DATEADD(DAY,-1, GETDATE())),
(1, 'STATE_2', DATEADD(DAY,-2, GETDATE())),
(1, 'STATE_3', DATEADD(DAY,-5, GETDATE())),
(2, 'STATE_1', NULL),
(2, 'STATE_2', GETDATE());
WITH MAX_DATES AS (
SELECT ID, MAX(EVENT_TS) AS MAX_EVENT_TS
FROM #TAB1
GROUP BY ID
)
SELECT MD.ID,
T.MY_STATE,
MD.MAX_EVENT_TS AS EVENT_TS
FROM MAX_DATES AS MD
INNER JOIN #TAB1 AS T
ON MD.ID = T.ID
AND MD.MAX_EVENT_TS = T.EVENT_TS
ORDER BY MD.ID;
DROP TABLE #TAB1;
Steve (aka sgmunson) 🙂 🙂 🙂
Rent Servers for Income (picks and shovels strategy)
December 5, 2018 at 9:35 am
Hi smugson,
I'm sorry but it doesn't do the trick:
CREATE TABLE #TAB1(
ID INT
,MY_STATE VARCHAR(10)
,EVENT_TS DATETIME
)
INSERT INTO #TAB1(ID, MY_STATE, EVENT_TS)
VALUES (1, 'STATE_1', GETDATE())
,(1, 'STATE_1', DATEADD(DAY,-1, GETDATE()))
,(1, 'STATE_2', DATEADD(DAY,-2, GETDATE()))
,(1, 'STATE_2', DATEADD(DAY,2, GETDATE()))
,(1, 'STATE_3', DATEADD(DAY,-5, GETDATE()))
,(2, 'STATE_1', NULL)
,(2, 'STATE_2', GETDATE())
,(2, 'STATE_3', DATEADD(DAY,2,GETDATE()))
Your query returns STATE_3 for the ID 2, while I'd like to see STATE_2 paired with ID: 2
December 6, 2018 at 9:19 am
Data Cruncher - Wednesday, December 5, 2018 9:35 AMHi smugson,
I'm sorry but it doesn't do the trick:
CREATE TABLE #TAB1(
ID INT
,MY_STATE VARCHAR(10)
,EVENT_TS DATETIME
)INSERT INTO #TAB1(ID, MY_STATE, EVENT_TS)
VALUES (1, 'STATE_1', GETDATE())
,(1, 'STATE_1', DATEADD(DAY,-1, GETDATE()))
,(1, 'STATE_2', DATEADD(DAY,-2, GETDATE()))
,(1, 'STATE_2', DATEADD(DAY,2, GETDATE()))
,(1, 'STATE_3', DATEADD(DAY,-5, GETDATE()))
,(2, 'STATE_1', NULL)
,(2, 'STATE_2', GETDATE())
,(2, 'STATE_3', DATEADD(DAY,2,GETDATE()))Your query returns STATE_3 for the ID 2, while I'd like to see STATE_2 paired with ID: 2
Have you tried the other solutions that were posted? I believe that mine does work, but it appears that you have not even considered it.
Drew
J. Drew Allen
Business Intelligence Analyst
Philadelphia, PA
December 7, 2018 at 4:42 am
Thanks Drew, actually your solution works well for the given dataset, but it assumes facts about data:
If tomorrow my user decides to rename the states State_Z and State_A instead of State_1 and State_2, or if a user violates the assumption about the dates (State_1 date < State_2 date), I'm busted.
December 7, 2018 at 5:12 am
Data Cruncher - Friday, December 7, 2018 4:42 AMThanks Drew, actually your solution works well for the given dataset, but it assumes facts about data:
If tomorrow my user decides to rename the states State_Z and State_A instead of State_1 and State_2, or if a user violates the assumption about the dates (State_1 date < State_2 date), I'm busted.
Which is why you should provide all necessary 'facts' up front instead of drip-feeding them. If you don't mention them, how is anyone (apart from you) going to know?
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.
December 7, 2018 at 6:54 am
@Phil
You're right Phil. In an attempt to remove unnecessary details from a much more complex query, I forgot to mention some important aspects of the problem.
I'll try to be more precise with next posts.
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