Given two tables...
tblEvents (fldEventID, fldAECap, fldDWCap, fldWSCap)
tblSignUps (fldSignUpID, fldEventID, fldPosition)
where a value of 1 in fldPosition relates to fldAECap, a value of 2 relates to fldDWCap, a value of 3 relates to fldWSCap; I need to prevent any new records from being inserted into tblSignUps if the count of fldPosition values is equal to each related CAP value. For instance, we may only have 3 allotted positions for fldAECAP and that position value occurs 3 times in fldPosition for that given EventID
The basic logic would come down to...
INSERT INTO tblSignUps
VALUES(NULL,12,3)
WHERE fldWSCap > COUNT(fldPosition(3))
How would I do this?
A way to write the required basic logic is this:
INSERT INTO tblSignUps
select NULL,12,3 from dual
where exists (
select * from tblEvents where
fldEventId = 12 and
fldWSCap > (select count(*) from tblSignUps where fldEventId = 12 and fldPosition = 3)
);
Obviously this works only for the field fldWSCap. The others two require a similar statement where the fld*Cap change according to the fldPosition value.
Related
Table Data:
ID
Type
1
A
2
A
3
B
4
A
5
A
6
B
7
B
8
A
9
A
10
A
How to get only rows with IDs 1,3,4,6,8, or the first records on type-change by single query?
We were doing this in code using multiple queries and extensive processing especially for large data, is there a way to do this in a single query?
Use LAG() window function to get for every row the previous row's type and compare it to the current type.
Create a flag column that is true if the 2 types are different and use it to filter the table:
WITH cte AS (
SELECT *, type <> LAG(type, 1, '') OVER (ORDER BY id) flag
FROM tablename
)
SELECT * FROM cte WHERE flag;
I assume that the column type does not contain empty values (nulls or
empty strings).
See the demo.
Hopefully I can explain this clearly. I have a table that has what need to be unique IDs for people within a group. The IDs are generated using first 3 letters of the first name and date of birth. Normally, with smaller groups (less than 500) this works fine. However in large groups we do hit upon some duplicates. We'd then just append a -1, -2, -3 etc. to any duplicate IDs. For example:
ID GROUP UID FIRST_NAME
1 123456 ALE19900123 ALEXIS
2 123456 ALE19900123 ALEXANDER
3 123456 ALE19900123 ALEJANDRO
4 789789 ALE19900123 ALEX
What I'd like to do is for ID 2 and 3 append a -1 and -2 respectively to their UID field so that 1,2 and 3 are now unique (GROUP + UID). ID 4 would be ignored because the GROUP is different
I've started with something like this:
UPDATE table A
JOIN table B
ON B.GROUP = A.GROUP
AND B.UID = A.UID
AND B.FIRST_NAME <> A.FIRST_NAME
AND B.ID < A.ID
SET A.duplicate_record = 1;
That should set the duplicate_record field = 1 for IDs 2 and 3. But then I still need to append a -1, -2, -3 etc. to those UIDs and I'm not sure how to do that. Maybe instead of just setting a flag = 1 for duplicate I should set the count of records that are duplicates?
If group, UID tuple is unique (and it should be), why not insert ignore the first one (without any value appended), check for how many rows were affected by SELECT ROW_COUNT();, and if that is zero, append -1? If you put it in a for cycle (pseudocode):
while i < 1000 do
insert ignore into people (group, uid, first_name) values (123456, concat(their_uid, "-", i), first name);
if ((select row_count();) == 1):
break;
i=i+1;
end while;
I am trying to find a reliable query which returns the first instance of an acceptable insert range.
Research:
some of the below links adress similar questions, but I could get none of them to work for me.
Find first available date, given a date range in SQL
Find closest date in SQL Server
MySQL difference between two rows of a SELECT Statement
How to find a gap in range in SQL
and more...
Objective Query Function:
InsertRange(1) = (StartRange(i) - EndRange(i-1)) > NewValue
Where InsertRange(1) is the value the query should return. In other words, this would be the first instance where the above condition is satisfied.
Table Structure:
Primary Key: StartRange
StartRange(i-1) < StartRange(i)
StartRange(i-1) + EndRange(i-1) < StartRange(i)
Example Dataset
Below is an example User table (3 columns), with a set range distribution. StartRanges are always ordered in a strictly ascending way, UserID are arbitrary strings, only the sequences of StartRange and EndRange matters:
StartRange EndRange UserID
312 6896 user0
7134 16268 user1
16877 22451 user2
23137 25142 user3
25955 28272 user4
28313 35172 user5
35593 38007 user6
38319 38495 user7
38565 45200 user8
46136 48007 user9
My current Query
I am trying to use this query at the moment:
SELECT t2.StartRange, t2.EndRange
FROM user AS t1, user AS t2
WHERE (t1.StartRange - t2.StartRange+1) > NewValue
ORDER BY t1.EndRange
LIMIT 1
Example Case
Given the table, if NewValue = 800, then the returned answer should be 23137. This means, the first available slot would be between user3 and user4 (with an actual slot size = 813):
InsertRange(1) = (StartRange(i) - EndRange(i-1)) > NewValue
InsertRange = (StartRange(6) - EndRange(5)) > NewValue
23137 = 25955 - 25142 > 800
More Comments
My query above seemed to be working for the special case where StartRanges where tightly packed (i.e. StartRange(i) = StartRange(i-1) + EndRange(i-1) + 1). This no longer works with a less tightly packed set of StartRanges
Keep in mind that SQL tables have no implicit row order. It seems fair to order your table by StartRange value, though.
We can start to solve this by writing a query to obtain each row paired with the row preceding it. In MySQL, it's hard to do this beautifully because it lacks the row numbering function.
This works (http://sqlfiddle.com/#!9/4437c0/7/0). It may have nasty performance because it generates O(n^2) intermediate rows. There's no row for user0; it can't be paired with any preceding row because there is none.
select MAX(a.StartRange) SA, MAX(a.EndRange) EA,
b.StartRange SB, b.EndRange EB , b.UserID
from user a
join user b ON a.EndRange <= b.StartRange
group by b.StartRange, b.EndRange, b.UserID
Then, you can use that as a subquery, and apply your conditions, which are
gap >= 800
first matching row (lowest StartRange value) ORDER BY SB
just one LIMIT 1
Here's the query (http://sqlfiddle.com/#!9/4437c0/11/0)
SELECT SB-EA Gap,
EA+1 Beginning_of_gap, SB-1 Ending_of_gap,
UserId UserID_after_gap
FROM (
select MAX(a.StartRange) SA, MAX(a.EndRange) EA,
b.StartRange SB, b.EndRange EB , b.UserID
from user a
join user b ON a.EndRange <= b.StartRange
group by b.StartRange, b.EndRange, b.UserID
) pairs
WHERE SB-EA >= 800
ORDER BY SB
LIMIT 1
Notice that you may actually want the smallest matching gap instead of the first matching gap. That's called best fit, rather than first fit. To get that you use ORDER BY SB-EA instead.
Edit: There is another way to use MySQL to join adjacent rows, that doesn't have the O(n^2) performance issue. It involves employing user variables to simulate a row_number() function. The query involved is a hairball (that's a technical term). It's described in the third alternative of the answer to this question. How do I pair rows together in MYSQL?
I think I am getting turned around when looking at this. I am trying to get all patron records relating to transactions that have a transaction item with one of a number of ids (1 or 2) as well as transaction items with other ids (3 or 4) but not with transaction items with other ids (5 or 6)
The structure is:
=patron=
id
fname
lname
email
phone
=trans=
id
id_org
id_patron
=trans_item=
id
id_trans
id_perf
I was trying the following:
SELECT
patron.email,
patron.fname,
patron.lname,
patron.phone
FROM
trans_item,
trans,
patron
WHERE
trans_item.id_perf IN (1,2)
AND
trans_item.id_perf IN (3,4)
AND
trans_item.id_perf NOT IN (5,6)
AND
trans_item.id_trans = trans.id
AND
trans.id_org = 1
AND
trans.id_patron = patron.id
GROUP BY
patron.id
ORDER BY
patron.email DESC,
patron.phone DESC
I'm aware that saying the id needs to be 2 AND 4 is always going to return nothing but I need to have it as if id is in (1,2) AND (3,4) so it can be 1 or 2 but also needs to be in 3 or 4
For Clarity:
I am trying to get patrons who have gone to performance 1 OR 2 and 3 OR 4 but NOT 5 OR 6
You can do this with group by and having. The basic idea is:
select ti.id_trans
from trans_item ti
group by ti.id_trans
having sum(ti.id_perf in (1, 2)) > 0 and
sum(ti.id_perf in (3, 4)) > 0 and
sum(ti.id_perf in (5, 6)) = 0;
Each condition in the having clause checks a row for the particular ids. The > 0 means they exist for transaction. The = 0 means they do not.
If you want additional columns from other tables, you can join back to this result set.
I think I have a solution. If I combine the ids for all perfs and group all results by the trans_item.id I can get a list that has duplicates. I then convert them into a php multidimensional array and exclude / include based on the ids for each requirement finding the duplicates that way. Any other suggestions are welcome
I have a table tbl_usertests from which i want to retrieve the user who have maximum testscore for each test.
Note: User here means usertestid which is unique.
Its colums are:
pk_usertestid attemptdate uploaddate fk_tbl_tests_testid fk_tbl_users_userid testscore totalquestionsnotattempted totalquestionscorrect totalquestionsincorrect totalquestions timetaken iscurrent
data :
1;NULL;"2010-06-24 22:48:07";"11";"3";"1";"53";"1";"21";"75";"92";"1"
2;NULL;"2010-06-25 01:21:37";"11";"4";"13";"0";"13";"62";"75";"801";"1"
3;NULL;"2010-06-25 01:21:50";"10";"4";"17";"5";"17";"53";"75";"640";"1"
4;NULL;"2010-06-25 01:24:23";"11";"4";"13";"0";"13";"62";"75";"801";"1"
5;NULL;"2010-06-25 01:24:47";"10";"4";"17";"5";"17";"53";"75";"640";"1"
6;NULL;"2010-06-25 01:36:04";"11";"5";"13";"0";"13";"62";"75";"801";"1"
7;NULL;"2010-06-25 01:47:26";"7";"5";"10";"1";"10";"49";"60";"302";"1"
My Query is :
SELECT max(`testscore`) , `fk_tbl_tests_testid` , `fk_tbl_users_userid` , `pk_usertestid`
FROM `tbl_usertests`
GROUP BY `fk_tbl_tests_testid`
This query output:
max(`testscore`) fk_tbl_tests_testid fk_tbl_users_userid pk_usertestid
10 7 5 7
17 10 4 3
13 11 3 1
But the problem is that if there are two users who have same score, it displays only one user because i have used group by clause.
For. e.g. testid =10 i have two records(pk_usertestid 3 and 5) but it displays 3 only.
I want the user whose upload date is less than the other user(in case of two users having same testscore). It should display for usertestid=3 since 3 upload date is less than 5.
Right now its displaying 3 but it is due to group by clause.
I am unable to construct the query.
Please help me on this
Thanks
Try this:
SELECT t.`fk_tbl_tests_testid` , t.`fk_tbl_users_userid` , t.`pk_usertestid`, maxscores.maxscore
FROM `tbl_usertests` t
JOIN (SELECT `fk_tbl_tests_testid`,max(`testscore`) as maxscore
FROM `tbl_usertests`
GROUP BY `fk_tbl_tests_testid`) maxscores ON t.`fk_tbl_tests_testid` = maxscores.`fk_tbl_tests_testid`
the logic behind is to separate the whole thing into two parts: get the maximum (or any other aggregate) values for each group (this is the subquery part), then for each element, join the corresponding aggregate. (JOIN it back to the riginal table)