I am new to MS ACCESS and am having trouble trying to get the number of records from overlapping time ranges. This is an example of my data.
example of raw data
I am trying to do is to get the column number_of_records. For example, if there are 4 records added at 5.11, the number_of_records should become 8 as 4 records are added at 5.10.
example of raw data with no_of_records column
There is a mistake in my image above. I forgot to mention that for example, if the time hits 6:00, the number of records should not add on to the previous records and should start afresh.
Do any of you have any suggestions?
Consider the correlated count subquery:
SELECT t.time_column_1, t.time_column_2,
(SELECT Count(*) FROM myTable sub
WHERE sub.time_column_1 <= t.time_column_1
AND sub.time_column_2 = t.time_column_2) AS number_of_records
FROM mytable t
ORDER BY t.time_column_2, t.time_column_1
Related
What would be the best way to check if there has been data within a 3 month period up until a maximum of 600 records, then repeat for the 3 months before that if 600 hasn't been reached? Also it's a large table so querying the whole thing could take a few minutes or completely hang Oracle SQL Developer.
ROWNUM seems to give row numbers to the whole table before returning the result of the query, so that seems to take too long. The way we are currently doing it is entering a time period explicitly that we guess there will be enough records within and then limiting the rows to 600. This only takes 5 seconds, but needs to be changed constantly.
I was thinking to do a FOR loop through each row, but am having trouble storing the number of results outside of the query itself to check whether or not 600 has been reached.
I was also thinking about creating a data index? But I don't know much about that. Is there a way to sort the data by date before grabbing the whole table that would be faster?
Thank you
check if there has been data within a 3 month period up until a maximum of 600 records, then repeat for the 3 months before that if 600 hasn't been reached?
Find the latest date and filter to only allow the rows that are within 6 months of it and then fetch the first 600 rows:
SELECT *
FROM (
SELECT t.*,
MAX(date_column) OVER () AS max_date_column
FROM table_name t
)
WHERE date_column > ADD_MONTHS( max_date_column, -6 )
ORDER BY date_column DESC
FETCH FIRST 600 ROWS ONLY;
If there are 600 or more within the latest 3 months then they will be returned; otherwise it will extend the result set into the next 3 month period.
If you intend to repeat the extension over more than two 3-month periods then just use:
SELECT *
FROM table_name
ORDER BY date_column DESC
FETCH FIRST 600 ROWS ONLY;
I was also thinking about creating a data index? But I don't know much about that. Is there a way to sort the data by date before grabbing the whole table that would be faster?
Yes, creating an index on the date column would, typically, make filtering the table faster.
The problem I'm dealing with involves a drilling database. The table has two columns, the first with the depth recorded by a sensor and the second with a timestamp. During the drilling, the equipment might be returned back up in order to have its bit changed.
I'm trying to make a query that would describe how long it takes to drill each meter (0-1; 1-2; 2-3), for example:
The problem I'm facing is that when making this comparison between rows in SQL Server, if I try comparing max(Timestamp) after grouping I end up including the data from when the bits return, which I don't want to do.
Select
Case when a.depth > 0 and a.depth <= 1 then '0-1'
when depth > 1 and depth <= 2 then '1-2' -- and so on until 10m where it ends…
end as 'Class',
(max(Timestamp) - min(Timestamp)) as 'Duration'
from Table
group by Class
order by Class
Does anyone know how to make this comparison between rows of the same column? Basically, it needs to ignore any values that are lower than its last maximum.
I have a table as below.
Somehow I want to calculate the idle time between End Date and Start Date.
Example: Idle time between 11:38:30 with 11:40:08, 11:49:35 with 12:00:19.
The problem is the station index number 5. It has a null value in 2 columns so I want to calculate base on the previous row
If you only need one value for each station, than grouping will work:
select
StationIndex,
max(Statoin_End_Date) - min(Station_Start_Date) as Duration
from table_name
group by StationIndex
Otherwise please explain logic in greater details.
I have created 2 tables. one table has 4 fields. a unique name, a date and 3 figures. The second table contains the same fields but records the output of a merge function. therefore has a date at which time the update or insert function happened. what I want to do is retrieve a sum of either the difference between 2 days or alternatively the totals of the 2 days to work out how much the value has changed over the day. The merge function only updates if a value has changed or it needs to insert a new value.
so far I have this
select sum(Change_Table_1.Disk_Space) as total,
Change_Table_1.Date_Updated
from VM_Info
left join Change_Table_1
on VM_Info.VM_Unique = Change_Table_1.VM_Unique
where VM_Info.Agency = 'test'
group by Change_Table_1.Date_Updated
but this would just return the sum of that days updated total rather than the difference between the two days. One answer to this question would be to to add all new records to the table but this would contain a number of duplicates. So in my head what I want it to do is loop over the current figures for the day then loop over the next day but also to include all values that haven't updated. sorry if I haven't explained this well. so what I want to achieve is to get some sort of change of the total over time. If its poor design im in a position to accept that also.
Any help is much appreciated.
maybe this would explain it better. show me total for day 1, if the value hasn't changed then show me the same value for day 2 if it has changed show me new value. and so on...
ok to further elaborate.
the Change_Table looks like
vm date created action value_Field1 value_field_2 Disk_Space
abc 14/10/2013 insert 5 5 30
def 14/10/2013 insert 5 5 75
abc 15/10/2013 update 5 5 75
so the out put I want is for the 14th the total for the last column is 105. On the 15th abc has changed from 30 to 75 but def hasn't changed but still neds to be included giving 150
so the output would look like
date disk_Space
14/10/2013 105
15/10/2013 150
Does this help? If not, can you provide a few rows of sample data, and an example of the desired result?
select
(VM_Info.Disk_Space - Change_Table_1.Disk_Space) as DiskSpaceChange,
Change_Table_1.Date_Updated
from
VM_Info
left join Change_Table_1 on VM_Info.VM_Unique = Change_Table_1.VM_Unique and VM_Info.Date = Change_Table_1.Date_Updated
where
VM_Info.Agency = 'test'
I have a table with 4 columns, id, Stream which is text, Duration (int), and Timestamp (datetime). There is a row inserted for every time someone plays a specific audio stream on my website. Stream is the name, and Duration is the time in seconds that they are listening. I am currently using the following query to figure up total listen hours for each week in a year:
SELECT YEARWEEK(`Timestamp`), (SUM(`Duration`)/60/60) FROM logs_main
WHERE `Stream`="asdf" GROUP BY YEARWEEK(`Timestamp`);
This does what I expect... presenting a total of listen time for each week in the year that there is data.
However, I would like to build a query where I have a result row for weeks that there may not be any data. For example, if the 26th week of 2006 has no rows that fall within that week, then I would like the SUM result to be 0.
Is it possible to do this? Maybe via a JOIN over a date range somehow?
The tried an true old school solution is to set up another table with a bunch of date ranges that you can outer join with for the grouping (as in the other table would have all of the weeks in it with a begin / end date).
In this case, you could just get by with a table full of the values from YEARWEEK:
201100
201101
201102
201103
201104
And here is a sketch of a sql statement:
SELECT year_weeks.yearweek , (SUM(`Duration`)/60/60)
FROM year_weeks LEFT OUTER JOIN logs_main
ON year_weeks.yearweek = logs_main.YEARWEEK(`Timestamp`)
WHERE `Stream`="asdf" GROUP BY year_weeks.yearweek;
Here is a suggestion. might not be exactly what you are looking for.
But say you had a simple table with one column [year_week] that contained the values of 1, 2, 3, 4... 52
You could then theoretically:
SELECT
A.year_week,
(SELECT SUM('Duration')/60/00) FROM logs_main WHERE
stream = 'asdf' AND YEARWEEK('TimeStamp') = A.year_week GROUP BY YEARWEEK('TimeStamp'))
FROM
tblYearWeeks A
this obviously needs some tweaking... i've done several similar queries in other projects and this works well enough depending on the situation.
If your looking for a one table/sql based solution then that is deffinately something I would be interested in as well!