Suppose I have table project which has following fields:
number of issue
number of comments
number of followers
created_at
I want to sort project on basis of all the fields, however each field has different precedence. A project with higher issue should be higher up even if it has lesser number of comments or followers.
Assume order of precedence to be:
issue > followers > comments > created_at
I can't use something like:
Select * from Projects ORDER BY Issue, Followers, Comments, Created_at
This would first order by issues and then solve conflicts on basis of followers and so on. For ex: I would want a project with 5 issues and 10 comments to be placed lower than one with 3 issues but 50 comments.
I guess I would need to use some multiplicative factor to scale everything in proportion. However, I can't figure out details.
Assume: 1 issue = 2 followers = 4 comments = 1 week old created at time
Something like this perhaps?
Select * from Projects
ORDER BY Issue * 5 + Followers * 3 + Comments DESC, Created_at
Related
ID MOBILE
1 9869600733
2 9869600793
3 9869600799
all id whose mobile number containing 9 three times... ?
Your RDBMS is needed to know the EXACT solution, but this works for most. I used MOBILE_ID_TABLE because you didn't provide table name. Depending on your RDBMS LIKE will want % or *.
SELECT ID FROM MOBILE_ID_TABLE WHERE MOBILE LIKE '%9%9%9%';
SELECT ID FROM MOBILE_ID_TABLE WHERE MOBILE LIKE '*9*9*9*';
my solution would be:
the statement will return all records, where the MOBILE column includes three times the number 9.
SELECT *
FROM youtable
WHERE (LEN(MOBILE) - LEN(REPLACE(MOBILE,'9',''))) = 3
What I am trying to do is fairly simple. I just want to add a row number to a query. Since this is in Access is a bit more difficult than other SQL, but under normal circumstances is still doable using solutions such as DCount or Select Count(*), example here: How to show row number in Access query like ROW_NUMBER in SQL or Access SQL how to make an increment in SELECT query
My Issue
My issue is I'm trying to add this counter to a multi-join query that orders by fields from numerous tables.
Troubleshooting
My code is a bit ridiculous (19 fields, seven of which are long expressions, from 9 different joined tables, and ordered by fields from 5 of those tables). To make things simple, I have an simplified example query below:
Example Query
SELECT DCount("*","Requests_T","[Requests_T].[RequestID]<=" & [Requests_T].[RequestID]) AS counter, Requests_T.RequestHardDeadline AS Deadline, Requests_T.RequestOverridePriority AS Priority, Requests_T.RequestUserGroup AS [User Group], Requests_T.RequestNbrUsers AS [Nbr of Users], Requests_T.RequestSubmissionDate AS [Submitted on], Requests_T.RequestID
FROM (((((((Requests_T
INNER JOIN ENUM_UserGroups_T ON ENUM_UserGroups_T.UserGroups = Requests_T.RequestUserGroup)
INNER JOIN ENUM_RequestNbrUsers_T ON ENUM_RequestNbrUsers_T.NbrUsers = Requests_T.RequestNbrUsers)
INNER JOIN ENUM_RequestPriority_T ON ENUM_RequestPriority_T.Priority = Requests_T.RequestOverridePriority)
ORDER BY Requests_T.RequestHardDeadline, ENUM_RequestPriority_T.DisplayOrder DESC , ENUM_UserGroups_T.DisplayOrder, ENUM_RequestNbrUsers_T.DisplayOrder DESC , Requests_T.RequestSubmissionDate;
If the code above is trying to select a field from a table not included, I apologize - just trust the field comes from somewhere (lol i.e. one of the other joins I excluded to simply the query). A great example of this is the .DisplayOrder fields used in the ORDER BY expression. These are fields from a table that simply determines the "priority" of an enum. Example: Requests_T.RequestOverridePriority displays to the user as an combobox option of "Low", "Med", "High". So in a table, I assign a numerical priority to these of "1", "2", and "3" to these options, respectively. Thus when ENUM_RequestPriority_T.DisplayOrder DESC is called in order by, all "High" priority requests will display above "Medium" and "Low". Same holds true for ENUM_UserGroups_T.DisplayOrder and ENUM_RequestNbrUsers_T.DisplayOrder.
I'd also prefer to NOT use DCOUNT due to efficiency, and rather do something like:
select count(*) from Requests_T where Requests_T.RequestID>=RequestID) as counter
Due to the "Order By" expression however, my 'counter' doesn't actually count my resulting rows sequentially since both of my examples are tied to the RequestID.
Example Results
Based on my actual query results, I've made an example result of the query above.
Counter Deadline Priority User_Group Nbr_of_Users Submitted_on RequestID
5 12/01/2016 High IT 2-4 01/01/2016 5
7 01/01/2017 Low IT 2-4 05/06/2016 8
10 Med IT 2-4 07/13/2016 11
15 Low IT 10+ 01/01/2016 16
8 Low IT 2-4 01/01/2016 9
2 Low IT 2-4 05/05/2016 2
The query is displaying my results in the proper order (those with the nearest deadline at the top, then those with the highest priority, then user group, then # of users, and finally, if all else is equal, it is sorted by submission date). However, my "Counter" values are completely wrong! The counter field should simply intriment +1 for each new row. Thus if displaying a single request on a form for a user, I could say
"You are number: Counter [associated to RequestID] in the
development queue."
Meanwhile my results:
Aren't sequential (notice the first four display sequentially, but then the final two rows don't)! Even though the final two rows are lower in priority than the records above them, they ended up with a lower Counter value simply because they had the lower RequestID.
They don't start at "1" and increment +1 for each new record.
Ideal Results
Thus my ideal result from above would be:
Counter Deadline Priority User_Group Nbr_of_Users Submitted_on RequestID
1 12/01/2016 High IT 2-4 01/01/2016 5
2 01/01/2017 Low IT 2-4 05/06/2016 8
3 Med IT 2-4 07/13/2016 11
4 Low IT 10+ 01/01/2016 16
5 Low IT 2-4 01/01/2016 9
6 Low IT 2-4 05/05/2016 2
I'm spoiled by PLSQL and other software where this would be automatic lol. This is driving me crazy! Any help would be greatly appreciated.
FYI - I'd prefer an SQL option over VBA if possible. VBA is very much welcomed and will definitely get an up vote and my huge thanks if it works, but I'd like to mark an SQL option as the answer.
Unfortuantely, MS Access doesn't have the very useful ROW_NUMBER() function like other clients do. So we are left to improvise.
Because your query is so complicated and MS Access does not support common table expressions, I recommend you follow a two step process. First, name that query you already wrote IntermediateQuery. Then, write a second query called FinalQuery that does the following:
SELECT i1.field_primarykey, i1.field2, ... , i1.field_x,
(SELECT field_primarykey FROM IntermediateQuery i2
WHERE t2.field_primarykey <= t1.field_primarykey) AS Counter
FROM IntermediateQuery i1
ORDER BY Counter
The unfortunate side effect of this is the more data your table returns, the longer it will take for the inline subquery to calculate. However, this is the only way you'll get your row numbers. It does depend on having a primary key in the table. In this particular case, it doesn't have to be an explicitly defined primary key, it just needs to be a field or combination of fields that is completely unique for each record.
I have an interesting question to ask you :)
Assumptions:
I am using Spring and Hibernate over Postgres database.
I have User table and every user has it's name and it's score.
I want to generate a sort of a rank where: Given the user's name I extrapolate 5 users that have more scores than the given user and 5 users that have less scores like this:
user1 p.105
user2 p.104
user3 p.103
user4 p.102
given user p.100
user6 p.99
user7 p.98
...
My question is: is it possible to make it in one query only? Will it be more optimal and faster in one query? Do you have any proposal of such a query?
Doing it in two queries is very simple but I want to know if there is a way to do it in one time?
PostgreSQL can do that with a single query. You might need to use native (raw) SQL in Hibernate. Here's one way.
with lowers as (
select *
from test
where score < (select score from test where user_id = 13)
limit 5
), highers as (
select *
from test
where score > (select score from test where user_id = 13)
limit 5
)
select * from lowers
union all
select * from highers
union all
select * from test where user_id = 13
order by score;
You should think about what should happen if there aren't five scores greater or five scores less than the target (user_id = 13). Also, this query won't bring in any rows that have scores identical to the target, which might or might not be what you're looking for. It also makes no attempt to get the 10 rows that are closest to the target.
On my dev box, which is no speedster, this query runs in 0.1 ms on a table of a million rows.
I'm developing a system using Trac, and I want to limit the number of "changelog" entries returned. The issue is that Trac collates these entries from multiple tables using a union, and then later combines them into single 'changesets' based on their timestamp. I wish to limit the results to the latest e.g. 3 changesets, but this requires retrieving as many rows as necessary until I've got 3 unique timestamps. Solution needs to work for SQLite/Postgres.
Trac's current SQL
Current SQL Result
Time User Field oldvalue newvalue permanent
=======================================================================
1371806593507544 a owner b c 1
1371806593507544 a comment 2 lipsum 1
1371806593507544 a description foo bar 1
1371806593324529 b comment hello world 1
1371806593125677 c priority minor major 1
1371806592492812 d comment x y 1
Intended SQL Result (Limited to 1 timestamp e.g.)
Time User Field oldvalue newvalue permanent
=======================================================================
1371806593507544 a owner b c 1
1371806593507544 a comment 2 lipsum 1
1371806593507544 a description foo bar 1
As you already pointed out on your own, this cannot be resolved in SQL due to the undetermined number of results. And I think this is not even required.
You can use a slightly modified trac/ticket/templates/ticket.html Genshi template to get what you want. Change
<div id="changelog">
<py:for each="change in changes">
into
<div id="changelog">
<py:for each="change in changes[-3:]">
and place the file into <env>/templates/ restart your web-server. But watch out for changes to ticket.html, whenever you attempt to upgrade your Trac install. Every time you do that, you might need to re-apply this change on the current template of the respective version. But IMHO its still a lot faster and cleaner than to patch Trac core code.
If you want just three records (as in the "Data Limit 1" result set), you can use limit:
select *
from t
order by time desc
limit 3
If you want all records for the three most recent time stamps, you can use a join:
select t.*
from t join
(select distinct time
from t
order by times desc
limit 3
) tt
on tt.time = t.time
I have the following fact table:
response_history_id client_id question_id answer
1 1 2 24
2 1 2 27
3 1 3 12
4 1 2 43
5 2 2 39
It holds history of client answers to some questions. The largest response_history_id for each client_id,question_id combination is the latest answer for that question and client.
What I want to do is to count the number of clients whose latest answer falls within a specific range
I have some dimensions:
question associated with question_id
client associated with client_id
response_history_id associated with response_history_id
range associated with answer. 0-20 low, 20-40 = medium, >40 is high
and some measures:
max_history_id as max(response_history_id)
clients_count as disticnt count(client_id)
Now, I want to group only the latest answers by range:
select
[ranges].members on 0,
{[Measures].[clients_count]} on 1
from (select [question].[All].[2] on 1 from [Cube])
What I get is:
Measures All low medium high
clients_count 2 0 2 1
But what I wanted (and I can't get) is the calculation based on the latest answer:
Measures All low medium high
clients_count 2 0 1 1
I understand why my query doesn't give me the desired result, it's more for demonstration purpose. But I have tried a lot of more complex MDX queries and still couldn't get any good result.
Also, I can't generate a static view from my fact table because later on I would like to limit the search by another column in fact table which is timestamp, my queries must eventually be able to get _the number of clients whose latest answer to a question before a given timestamp falls within a specific range.
Can anyone help me with this please?
I can define other dimensions and measures and I am using iccube.