My question is similar to this SO post however the difference is that I do not have a sequential ID column.
I have a table in the following form
ID | length
0 | 5
0 | 7
0 | 10
1 | 3
1 | 8
1 | 12
2 | 1
2 | 2
2 | 4
2 | 5
and I want to get the difference between successive rows in the length column grouped by the ID. So it should give
ID | length | difference
0 | 5 | NULL
0 | 7 | 2
0 | 10 | 3
1 | 3 | NULL
1 | 8 | 5
1 | 12 | 4
2 | 1 | NULL
2 | 2 | 1
2 | 4 | 2
2 | 5 | 1
I'm not sure how to go about doing this. I tried giving each ID a separate ID that is sequential, but it turned out to be way to complicated and I could not get it to work. Can someone suggest a better way of doing it?
Assuming (id,length) is UNIQUE...
SELECT x.*
, x.length - MAX(y.length) diff
FROM my_table x
LEFT
JOIN my_table y
ON y.id = x.id
AND y.length < x.length
GROUP
BY x.id
, x.length;
select a.id, a.length, b.length, b.length - a.length as difference
from mytable a, mytable b
where a.id=b.id
and b.length = (select min(length) from mytable where id=a.id and length > a.length)
Related
I have a table like this:
PK | IDs | name1 | name2
-------------------
1 | 1 | a | null
2 | 1 | a | x
3 | 2 | b | null
4 | 3 | c | z
5 | 2 | null | y
6 | 1 | null | x
7 | 2 | b | null
8 | 2 | null | null
And i want to execute a select in mySQL that give me an output like this:
PK | IDs | name1 | name2
-------------------
1 | 1 | a | x
2 | 1 | a | x
3 | 2 | b | y
4 | 3 | c | z
5 | 2 | b | y
6 | 1 | a | x
7 | 2 | b | y
8 | 2 | b | y
So all the rows with the same id have the same name1 and name2 checking the one that its not null to fill it, if there is no one, it will continue as null.
If you only have one value of name1 or name2 for a given ID value, you can use an aggregation function like MAX (or MIN) which will give you that value from all the value for that IDs in the table. Using a derived table with those values, you can JOIN to the original table to get the name1 and name2 values for each PK, IDs combination:
SELECT d.PK, d.IDs, m.name1, m.name2
FROM data d
JOIN (SELECT IDs, MAX(name1) AS name1, MAX(name2) AS name2
FROM data
GROUP BY IDs) m ON m.IDs = d.IDs
Output:
PK IDs name1 name2
1 1 a x
2 1 a x
3 2 b y
4 3 c z
5 2 b y
6 1 a x
7 2 b y
8 2 b y
Demo on SQLFiddle
You can use correlated sub-query :
select t.pk, t.ids,
coalesce(t.name1, (select t1.name1
from table t1
where t1.pk < t.pk and t1.name1 is not null
order by t1.pk desc
limit 1)
) as name1,
coalesce(t.name2, (select t1.name2
from table t1
where t1.pk < t.pk and t1.name2 is not null
order by t1.pk desc
limit 1)
) as name2
from table t;
You can use update with join:
update t join
(select id, max(name1) as name1, max(name2) as name2
from t
group by id
) tt
on t.id = tt.id
set t.name1 = coalesce(t.name1, tt.name1),
t.name2 = coalesce(t.name2, tt.name2)
where t.name1 is null or t.name2. is null;
Note: This will not change any values that are not NULL, so it is safe even if the values differ for a given id.
I am dealing with a table Employee Complaint which has columns EmployeeId ComplaintSeverity and ComplaintByUser. ComplaintSeverity has four level 0,1,2, and 3.
So the table will look like this ,Example
ComplaintId|EmployeeId|ComplaintSeverity|usr_id
-----------------------------------
1 | 1 | 0 | 3
2 | 2 | 1 | 4
3 | 3 | 0 | 5
4 | 1 | 2 | 4
5 | 4 | 1 | 5
6 | 2 | 2 | 2
7 | 2 | 2 | 4
Any user can complaint employee with any of these level
When client search with severitylevel as 0,
The row should fetch as
ComplaintId|EmployeeId|ComplaintSeverity
----------------------------
3 | 3 | 0
for severitylevel as 1,
ComplaintId|EmployeeId|ComplaintSeverity
----------------------------
5 | 4 | 1
for severitylevel as 2,
ComplaintId|EmployeeId|ComplaintSeverity
----------------------------
4 | 1 | 2
6 | 2 | 2
EmployeeId 1 has been complained by 2 user with severitylevel 0,2 but his highest severity level is 2. so while searching for 0 level, 1 should not be displayed.
Can anyone help me?
The question was edited after the previous answer was submitted. The following would therefore be more accurate.
SELECT x.*
FROM my_table x
JOIN
( SELECT employeeid
, MAX(complaintseverity) severity
FROM my_table
GROUP
BY employeeid
) y
ON y.employeeid = x.employeeid
AND y.severity = x.complaintseverity
WHERE complaintseverity = 0 -- optional line
ORDER
BY employeeid;
You can try following query.
SELECT *
FROM
(
SELECT cs.`EmployeeId`, MAX(cs.`ComplaintSeverity`) severity
FROM ComplaintSeverity cs
GROUP BY cs.`EmployeeId`
) csdata
WHERE csdata.severity=1
Replace 1 with the severity level you want.
Could you please tell me how to delete unknown number last record (on condition)?
For example, in this situation I want to delete record with id: 6 to 10.
Note: this table and records is not constant.
+----+-----+---------+
| id | url | emailid |
+----+-----+---------+
| 1 | 10 | 1 |
| 2 | 20 | 0 |
| 3 | 30 | 2 |
| 4 | 40 | 0 |
| 5 | 50 | 10 |
| 6 | 60 | 0 |
| 7 | 70 | 0 |
| 8 | 80 | 0 |
| 9 | 90 | 0 |
| 10 | 100 | 0 |
+----+-----+---------+
Thanks...
It seems that you want to delete the last set of records where all the values are 0. This is a bit of a pain. You can find the minimum such id as:
select min(t.id)
from table t
where t.emailid = 0 and
not exists (select 1 from table t2 where t2.id > t.id and t2.emailid <> 0);
The logic is: find all rows where emailid is 0 and there are no subsequent emailids that are not zero.
You can put this into a delete using join:
delete t
from table t cross join
(select min(t.id) as first0id
from table t
where t.emailid = 0 and
not exists (select 1 from table t2 where t2.id > t.id and t2.emailid <> 0)
) tmin
where t.id >= tmin.first0id;
You can use between keyword in your query like this
delete from yourtable where id BETWEEN 6 AND 10
use this query
delete from your_table where id between 6 AND 10
for not being constant you can first store start and end values in variable and then pass in query,example(in php)
$start = 6 ;
$end = 10;
query
"delete from your_table where id between $start AND $end"
I have an issue similar to this question:
updating columns with a sequence number mysql
However, I have a second column that also "sometimes" needs updated. For example, consider this table:
uID | X | Y
1 | 6 | 0
2 | 2 | 0
3 | 7 | 0
4 | 7 | 1
5 | 3 | 0
6 | 1 | 0
I would like 'X' re-ordered sequentially which I can do with the solution from the link, above:
SET #rank:=0;
UPDATE `myTable` SET
X = #rank:= #rank+1
ORDER BY X
However, if the record has Y values greater than 0 I need its X to be updated at the same time. The Y value, being the 2 dimensional value, needs to remain with its 'X'. Make sense? So I need the table to end up:
uID | X | Y
6 | 1 | 0
2 | 2 | 0
5 | 3 | 0
1 | 4 | 0
3 | 5 | 0
4 | 5 | 1
Ideas?
Try:
SET #rank:=0;
UPDATE `myTable` SET
X = #rank:= #rank + if(y=0,1,0)
ORDER BY X
demo--> http://www.sqlfiddle.com/#!2/f158e/1
Its very hard for to set a proper title, because I dont know how I describe my problem.
I have a table like this:
dlID | dl_seID | dlEpisode | dlFlag
___________________________________
1 | 1 | 1 | 0
2 | 1 | 2 | 1
3 | 1 | 3 | 1
4 | 2 | 1 | 1
5 | 2 | 2 | 0
6 | 3 | 1 | 0
What i want is a select query where I get something like this:
dlID | dl_seID | dlEpisode | dlFlag | dlFlagCount
_________________________________________________
1 | 1 | 1 | 0 | 2
2 | 1 | 2 | 1 | 2
3 | 1 | 3 | 1 | 2
4 | 2 | 1 | 1 | 1
5 | 2 | 2 | 0 | 1
6 | 3 | 1 | 0 | 0
dlFlagCount shoud be a counter of dlFlag = 1 where dl_seID = dl_seID.
Second try:
I need a value where I see how many Flags have the value 1 with the same dl_seID.
Is that possible?
I hope you guys know what I want^^
Regards
Try this:
select
a.*,
ifnull(b.ctflags,0)
from
tablea a left join
( select dl_seID, count(dlFlag) ctflags
from tablea
where dlFlag=1
group by dl_seID ) b on (a.dl_seID = b.dl_seID)
The left join is just to get the registry with 0 flags
See the fiddle: http://sqlfiddle.com/#!2/ef9b0/5
EDIT:
As op requested some explanation, here it goes:
What you asked is to count the amount of flags by the dl_seID and to do that you need to do this you separeta your problems, first you get the count for the dl_seID by flags, this is this subquery:
select dl_seID, count(dlFlag) ctflags
from tablea
where dlFlag=1
group by dl_seID
This became a 'separe table' or a new group of data, whatever you wanna call it. Then you have to join this with your original data (from your table) like the query for answer.
The left join part is because maybe there are some data that wont complain with where dlFlag=1 therefore if you want to get then as 0 you have to bring all values from table that exists or not on our created subgroup. And this ifnull(b.ctflags,0) is for theese data data exists on your table but has no flags (for your problem). If you use just b.ctflags it will bring null.
SELECT x.*
, COALESCE(y.flagcount,0) flagcount
FROM my_table x
LEFT
JOIN
( SELECT seID
, COUNT(*) flagcount
FROM my_table
WHERE flag = 1
GROUP
BY seid
) y
ON y.seid = x.seid;