Yes, I know this seems simple:
SELECT DISTINCT(...)
Except, it apparently isn't
Here is my actual Query:
SELECT
DeclinationReasons.Reason,
EmployeeInformation.ID,
EmployeeInformation.Employee,
EmployeeInformation.Active,
CompletedTrainings.DecShotDate,
CompletedTrainings.DecShotLocation,
CompletedTrainings.DecReason,
CompletedTrainings.DecExplanation,
IIf([DecShotLocation]="MCS","Yes","No") AS YesMCS,
IIf([DecReason]=1,1,0) AS YesAllergy,
IIf([DecReason]=2,1,0) AS YesImmune,
IIf([DecReason]=3,1,0) AS YesAdverse,
IIf([DecReason]=4,1,0) AS YesMedical,
IIf([DecReason]=5,1,0) AS YesSpiritual,
IIf([DecReason]=6,1,0) AS YesOther,
IIf([DecReason]=7,1,0) AS YesAlready
FROM
EmployeeInformation
INNER JOIN (CompletedTrainings
LEFT JOIN DeclinationReasons ON CompletedTrainings.DecReason = DeclinationReasons.ReasonID)
ON EmployeeInformation.ID = CompletedTrainings.Employee
GROUP BY
DeclinationReasons.Reason,
EmployeeInformation.ID,
EmployeeInformation.Employee,
EmployeeInformation.Active,
CompletedTrainings.DecShotDate,
CompletedTrainings.DecShotLocation,
CompletedTrainings.DecReason,
CompletedTrainings.DecExplanation,
IIf([DecShotLocation]="MCS","Yes","No"),
IIf([DecReason]=1,1,0),
IIf([DecReason]=2,1,0),
IIf([DecReason]=3,1,0),
IIf([DecReason]=4,1,0),
IIf([DecReason]=5,1,0),
IIf([DecReason]=6,1,0),
IIf([DecReason]=7,1,0)
HAVING
((((EmployeeInformation.Active) Like -1)
AND ((CompletedTrainings.DecShotDate + 365 >= DATE())
OR (CompletedTrainings.DecShotDate IS NULL))));
This is Joining a few tables (obviously) in order to get a number of records. The problem is that if someone is duplicated on the table with a NULL in one of the date fields, and a date in another field, it pulls both the NULL and the DATE, or pulls multiple NULLS it might pull multiple dates but those are not present right at the moment.
I need the Nulls, they are actual data in this particular case, but if someone has a date and a NULL I need to pull only the newest record, I thought I could add MAX(RecordID) from the table, but that didn't change the results of the query either.
That code:
SELECT
DeclinationReasons.Reason,
EmployeeInformation.ID,
EmployeeInformation.Employee,
EmployeeInformation.Active,
MAX(CompletedTrainings.RecordID),
CompletedTrainings.DecShotDate
...
And it returned the same issue, Duplicated EmployeeInformation.ID with different DecShotDate values.
Currently it returns:
ID
Active
DecShotDate
etc. x a bunch
1
-1
date date
whatever goes
2
-1
in these
2
-1
date date
columns
These are being used in a report, that is to determine the total number of employees who fit the criteria of the report. The NULLs in DecShotDate are needed as they show people who did not refuse to get a flu vaccine in the current year, while the dates are people who did refuse.
Now I have come up with one simple solution, I could add a column to the CompletedTrainings Table that contains a date or other value, and add that to the HAVING statement. This might be the right solution as this is a yearly training questionnaire that employees have to fill out. But I am asking for advice before doing this.
Am I right in thinking I need to add a column to filter by so that older data isn't being pulled, or should I be able to do this by pulling recordID, and did I just bork that part of the query up?
Edited to add raw table views:
EmployeeInformation Table:
ID
Last
First
empID
Active
Termdate
DoH
Title
PT/FT/PD
PI
1
Doe
Jane
982
-1
date
Sr
PD
X
2
Roe
John
278
0
date
date
Jr
PD
X
3
Moe
Larry
1232
-1
date
Sr
FT
X
4
Zoe
Debbie
1424
-1
date
Sr
PT
X
DeclinationReasons Table:
ReasonID
Reason
1
Allergy
2
Already got it
3
Illness
CompletedTrainings Table:
RecordID
Employee
Training
...
DecShotdate
DecShotLocation
DecShotReason
DecExp
1
1
4
date
location
2
text
2
1
4
3
2
4
4
3
4
date
location
3
text
5
3
4
date
location
1
text
6
4
4
After some serious soul searching, I decided to use another column and filter by that.
In the end my query looks like this:
SELECT *
FROM (
(
SELECT RecordID, DecShotDate, DecShotLocation, DecReason, DecExplanation, Employee,
IIf([DecShotLocation]="MCS","Yes","No") AS YesMCS, IIf([DecReason]=1,1,0) AS YesAllergy,
IIf([DecReason]=2,1,0) AS YesImmune, IIf([DecReason]=3,1,0) AS YesAdverse,
IIf([DecReason]=4,1,0) AS YesMedical, IIf([DecReason]=5,1,0) AS YesSpiritual,
IIf([DecReason]=6,1,0) AS YesOther, IIf([DecReason]=7,1,0) AS YesAlready
FROM CompletedTrainings WHERE (CompletedDate > DATE() - 365 ) AND (Training = 69)) AS T1
LEFT JOIN
(
SELECT ID, Active FROM EmployeeInformation) AS T2 ON T1.Employee = T2.ID)
LEFT JOIN
(
SELECT Reason, ReasonID FROM DeclinationReasons) AS T3 ON T1.DecReason = T3.ReasonID;
This may not have been the best solution, but it did exactly what I needed. Which is to get the information by latest entry into the database.
Previously I had tried to use MAX(), DISTINCT(), etc. but always had a problem of multiple records being retrieved. In this case, I intentionally SELECT the most recent records first, then join them to the results of the next query, and so on. Until I have all the required data for my report.
I write this in hopes someone else finds it useful. Or even better if someone tells me why this is wrong, so as to improve my own skills.
I have a table with multiple rows with a column for ordering these rows. And then I have an expired column and a data column:
|ordering| expired | data |
------------------------------
| 1 |2020-12-31|whatever|
| 2 |2020-12-31|whatever|
| 3 |2020-12-31|whatever|
| 4 |2010-01-01|whatever|
| 5 |2020-12-31|whatever|
I also have a table with the line number for which I last got:
|number|
|------|
| 2 |
I get that number and add 1 to get the next line I need. Then I check if that number is higher than the rowcount and got back to 1 if it is. I store the new line back into number so I can use that the next time I need a row.
This is working perfectly except I filter the results by expired. In the above example row 4 will not be selected. So when I get the row with ordering=4 then the result will be empty. Of course it is easy to fix - if I get an empty results I can just try the next value. This takes extra time and lots of extra time if there are lots of expired rows.
I also need to take care that I don't loose a row if a row I previously got happens to get expired between two calls.
What is the most effective way to iterate through rows when they could be constantly changing?
Running the query twice is possibly the best approach. But, you can also order all the results, starting with the first value after the number and wrapping around:
order by (case when t1.ordering > t2.number then 1 else 2 end),
t1.ordering
If you have 10 rows, then this is fine. If you have 10,000 then you incur the overhead of sorting all the data, and two queries are probably faster.
You could perform a query using Min(ordering):
SELECT #nextOrderingNum = Coalesce(Min(t1.ordering), 0)
FROM table1 t1
WHERE t1.expired > GETDATE()
AND t1.ordering > #prevOrderingNum;
If #nextOrderingNum is 0 set #prevOrderingNum = #nextOrderingNum and run again.
Edit, even better instead of running twice just add a sub-query to the Coalesce:
SELECT #nextOrderingNum = Coalesce(Min(t1.ordering),
(SELECT Min(t2.ordering) FROM table1 t2
WHERE t2.expired > GETDATE()))
FROM table1 t1
WHERE t1.expired > GETDATE()
AND t1.ordering > #prevOrderingNum;
I have an access database that I'm well aware is quite poorly designed, unfortunately it is what I must use. It looks a little like the following:
(Row# is not a column in the database, it's just there to help me describe what I'm after)
Row# ID Date Misc
1 001 01/8/2013 A
2 001 01/8/2013 B
3 001 01/8/2013 C
4 002 02/8/2013 D
5 002 02/8/2013 A
6 003 04/8/2013 B
7 003 04/8/2013 D
8 003 04/8/2013 D
What I'm trying to do is obtain all information entered for the last n (by date) 'entries' where an 'entry' is all rows with a unique ID.
So if I want the last 1 entry I will get rows 6, 7 and 8. The last two entries will get me rows 4-8 etc.
I've tried to get the SN's needed in a subselect and then select all entries where those SN's appear, but I couldn't get it to work. Any help appreciated.
Thanks.
The proper Access syntax:
select *
from t
where ID in (select top 10 ID
from t
group by ID
order by max([date]) desc
)
I think this will work:
select *
from table
where Date in (
select distinct(Date) as unique_date from table order by unique_date DESC limit <num>
)
The idea is to use the subselect with a limit to only identify dates you care about.
EDIT: Some databases do not allow a limit in a subquery (I'm looking at you, mysql). In that case, you'll have to make a temporary table out of the subquery then select * from it.
I have a table with few columns and I want to achieve the following functionality using DB2 query.
say for e.g. USR table has User ID column and Option ID column
USER ID OPTION ID
1 1
1 5
1 22
1 100
1 999
I want to write a query and result should be next available number in sequence.
So when the first time query will be executed, it should return me the next
available option ID as 2, so user will enter #2, so DB would have now
USER ID OPTION ID
1 1
1 2
1 5
1 22
1 100
1 999
so now when the query will be executed, it will show me available Option ID as 3.
Can somebody help to get the optimized query to get the correct results?
Please note that I think that exposing option_id to the user is a terrible idea, business requirement or no. Surrogate id's like this are meant to be completely hidden from the end user ('natural' keys, like credit-card numbers, obviously have to be exposed, but still shouldn't be dictated in this manner).
The following should work on any version of DB2:
SELECT a.optionid + :nextIncrement as next_value
FROM Usr as a
LEFT JOIN Usr as b
ON b.userid = a.userid
AND b.optionid = a.optionid + :nextIncrement
WHERE a.userid = :userId
AND b.userid IS NULL
ORDER BY a.optionid ASC
FETCH FIRST 1 ROW ONLY
(statement run against a local table on my iSeries instance, with host variables replaced)
Again, I strongly recommend you not use this, and see about getting the business requirement changed.
I Have an SQL query giving me X results, I want the query output to have a coulmn called
count making the query somthing like this:
count id section
1 15 7
2 3 2
3 54 1
4 7 4
How can I make this happen?
So in your example, "count" is the derived sequence number? I don't see what pattern is used to determine the count must be 1 for id=15 and 2 for id=3.
count id section
1 15 7
2 3 2
3 54 1
4 7 4
If id contained unique values, and you order by id you could have this:
count id section
1 3 2
2 7 4
3 15 7
4 54 1
Looks to me like mikeY's DSum approach could work. Or you could use a different approach to a ranking query as Allen Browne described at this page
Edit: You could use DCount instead of DSum. I don't know how the speed would compare between the two, but DCount avoids creating a field in the table simply to store a 1 for each row.
DCount("*","YourTableName","id<=" & [id]) AS counter
Whether you go with DCount or DSum, the counter values can include duplicates if the id values are not unique. If id is a primary key, no worries.
I frankly don't understand what it is you want, but if all you want is a sequence number displayed on your form, you can use a control bound to the form's CurrentRecord property. A control with the ControlSource =CurrentRecord will have an always-accurate "record number" that is in sequence, and that will update when the form's Recordsource changes (which may or may not be desirable).
You can then use that number to navigate around the form, if you like.
But this may not be anything like what you're looking for -- I simply can't tell from the question you've posted and the "clarifications" in comments.
The only trick I have seen is if you have a sequential id field, you can create a new field in which the value for each record is 1. Then you do a running sum of that field.
Add to your query
DSum("[New field with 1 in it]","[Table Name]","[ID field]<=" & [ID Field])
as counterthing
That should produce a sequential count in Access which is what I think you want.
HTH.
(Stolen from Rob Mills here:
http://www.access-programmers.co.uk/forums/showthread.php?p=160386)
Alright, I guess this comes close enough to constitute an answer: the following link specifies two approaches: http://www.techrepublic.com/blog/microsoft-office/an-access-query-that-returns-every-nth-record/
The first approach assumes that you have an ID value and uses DCount (similar to #mikeY's solution).
The second approach assumes you're OK creating a VBA function that will run once for EACH record in the recordset, and will need to be manually reset (with some VBA) every time you want to run the count - because it uses a "static" value to run its counter.
As long as you have reasonable numbers (hundreds, not thousands) or records, the second approach looks like the easiest/most powerful to me.
This function can be called from each record if available from a module.
Example: incrementingCounterTimeFlaged(10,[anyField]) should provide your query rows an int incrementing from 0.
'provides incrementing int values 0 to n
'resets to 0 some seconds after first call
Function incrementingCounterTimeFlaged(resetAfterSeconds As Integer,anyfield as variant) As Integer
Static resetAt As Date
Static i As Integer
'if reset date < now() set the flag and return 0
If DateDiff("s", resetAt, Now()) > 0 Then
resetAt = DateAdd("s", resetAfterSeconds, Now())
i = 0
incrementingCounterTimeFlaged = i
'if reset date > now increments and returns
Else
i = i + 1
incrementingCounterTimeFlaged = i
End If
End Function
autoincrement in SQL
SELECT (Select COUNT(*) FROM table A where A.id<=b.id),B.id,B.Section FROM table AS B ORDER BY B.ID Asc
You can use ROW_NUMBER() which is in SQL Server 2008
SELECT ROW_NUMBER() OVER (ORDER By ID DESC) RowNum,
ID,
Section
FROM myTable
Then RowNum displays sequence of row numbers.