Here's the situation. I created a view that has all the following information
CREATE VIEW view2 AS
SELECT activity_id,
subject_code,
academic_period_code,
DATEDIFF(HOUR,time_start,time_end) AS duration
FROM activity
Okay, now I'm trying to make a query that can produce two columns,
1. one with subject code and the academic_period code concatenated into one column
2. The second column contains the total number of duration for each subject that is in that academic period
So its like: CS123 in academic_period 121 has total of 5 hours activity. I'm fine with the first column but I've been wondering how do I get the 2nd column. If I use the SUM function it just totals up the column itself so I'm not sure how to deal with this.
Sample data
Subject Code Activity_code Academic_Period_Code Duration
CS123 1 121 2
CS123 2 121 3
CS123 3 122 2
CS123 4 122 2
What I have done?]
SELECT subject_code + academic_period_code AS subject,
(I think I have to do a subquery but I'm not sure how its suppose to work out) AS total_activity_time
FROM view2
Assuming SQL Server and that I understand what you are looking for:
select
subject_code + academic_period_code as [Type],
sum(duration) as duration
from view2
group by
subject_code + academic_period_code;
should get you where I think you're trying to get.
select
subject_code + academic_period_code as subjects,
sum(duration) as duration
from view2
group by
subject_code, academic_period_code;
Related
Hi so i am making a database and want to return only the minimum value and maximum value with other information in other columns so i want to display like the shopID and the brands and brand name
SELECT Shop.ShopID,
Brand.BrandID,
Brand.Brand_name,
price
FROM Brand
INNER JOIN Shop ON Brand.BrandID = Shop.BrandID
WHERE Brand.BrandID = 1
ORDER BY Price;
ShopID BrandID Brand_Name Price
18 1 coke 41
9 1 sprite 115
1 1 fanta 141
as you can see it shows me all 3 values i know all the brands are one 1 even though they are separate brands but i essentially want to remove the middle one so it only shows me the minimum and maximum values, just not sure how to go about this, any help would be greatly appreciated.
I think you can use MAX and MIN functions, please refer to this: https://www.w3schools.com/sql/sql_min_max.asp
Also you can check these threads:
SQL Functions using MIN and MAX together
How to return MAX and MIN of a value from a table?
You should use MIN and MAX on column name.
eg-SELECT MIN(column_name)
FROM table_name
WHERE your_condition;
Or
eg-SELECT MAX(column_name)
FROM table_name
WHERE your_condition;
Also if you want to use them together
SELECT
MIN(column_name) AS min_col,
MAX(column_name) AS max_col
FROM table_name;
I have a query that collects many different columns, and I want to include a column that sums the price of every component in an order. Right now, I already have a column that simply shows the price of every component of an order, but I am not sure how to create this new column.
I would think that the code would go something like this, but I am not really clear on what an aggregate function is or why I get an error regarding the aggregate function when I try to run this code.
SELECT ID, Location, Price, (SUM(PriceDescription) FROM table GROUP BY ID WHERE PriceDescription LIKE 'Cost.%' AS Summary)
FROM table
When I say each component, I mean that every ID I have has many different items that make up the general price. I only want to find out how much money I spend on my supplies that I need for my pressure washers which is why I said `Where PriceDescription LIKE 'Cost.%'
To further explain, I have receipts of every customer I've worked with and in these receipts I write down my cost for the soap that I use and the tools for the pressure washer that I rent. I label all of these with 'Cost.' so it looks like (Cost.Water), (Cost.Soap), (Cost.Gas), (Cost.Tools) and I would like it so for Order 1 it there's a column that sums all the Cost._ prices for the order and for Order 2 it sums all the Cost._ prices for that order. I should also mention that each Order does not have the same number of Costs (sometimes when I use my power washer I might not have to buy gas and occasionally soap).
I hope this makes sense, if not please let me know how I can explain further.
`ID Location Price PriceDescription
1 Park 10 Cost.Water
1 Park 8 Cost.Gas
1 Park 11 Cost.Soap
2 Tom 20 Cost.Water
2 Tom 6 Cost.Soap
3 Matt 15 Cost.Tools
3 Matt 15 Cost.Gas
3 Matt 21 Cost.Tools
4 College 32 Cost.Gas
4 College 22 Cost.Water
4 College 11 Cost.Tools`
I would like for my query to create a column like such
`ID Location Price Summary
1 Park 10 29
1 Park 8
1 Park 11
2 Tom 20 26
2 Tom 6
3 Matt 15 51
3 Matt 15
3 Matt 21
4 College 32 65
4 College 22
4 College 11 `
But if the 'Summary' was printed on every line instead of just at the top one, that would be okay too.
You just require sum(Price) over(Partition by Location) will give total sum as below:
SELECT ID, Location, Price, SUM(Price) over(Partition by Location) AS Summed_Price
FROM yourtable
WHERE PriceDescription LIKE 'Cost.%'
First, if your Price column really contains values that match 'Cost.%', then you can not apply SUM() over it. SUM() expects a number (e.g. INT, FLOAT, REAL or DECIMAL). If it is text then you need to explicitly convert it to a number by adding a CAST or CONVERT clause inside the SUM() call.
Second, your query syntax is wrong: you need GROUP BY, and the SELECT fields are not specified correctly. And you want to SUM() the Price field, not the PriceDescription field (which you can't even sum as I explained)
Assuming that Price is numeric (see my first remark), then this is how it can be done:
SELECT ID
, Location
, Price
, (SELECT SUM(Price)
FROM table
WHERE ID = T1.ID AND Location = T1.Location
) AS Summed_Price
FROM table AS T1
to get exact result like posted in question
Select
T.ID,
T.Location,
T.Price,
CASE WHEN (R) = 1 then RN ELSE NULL END Summary
from (
select
ID,
Location,
Price ,
SUM(Price)OVER(PARTITION BY Location)RN,
ROW_number()OVER(PARTITION BY Location ORDER BY ID )R
from Table
)T
order by T.ID
I have a table with roads that contain mileage of start/end of every road.
I need to analyze this data and get query with same data more rows that contain mileage of start/end of gaps between roads with filled column name with value 'gap'.
Initial table:
id name kmstart kmend
1 road1 0 150
2 road2 150 200
3 road3 220 257
4 road4 260 290
Result query:
id name kmstart kmend
1 road1 0 150
2 road2 150 200
null gap 200 220
3 road3 220 257
null gap 257 260
4 road4 260 290
Try this query:
SELECT NULL, 'gap', previous_kmend AS kmstart, kmstart AS kmend
FROM (
SELECT id, name, kmstart, kmend, LAG(kmend) OVER (ORDER BY kmstart, kmend) AS previous_kmend
FROM roads
)
WHERE previous_kmend < kmstart
UNION ALL
SELECT id, name, kmstart, kmend
FROM roads
ORDER BY kmstart, kmend
I just put up a quick test and it works for me.
It uses the LAG function to get the previous kmend row, and then returns the "gap" row if it is less than the current record's kmstart row. I've written an article about the LAG function recently so it was helpful to remember.
Is this what you're after?
Also, as the other commenters have mentioned, "name" isn't a good column name as it's a reserved word. I've left it here in the code so it's consistent with your question though.
Firstly, I could not think of a better question title. Apologies for that.
So, I am writing a query and here is something(I think) it would return without aggregating functions and group by. I am using this as an example and actual query contains a lot more fields:
SUBJ CLASSROOM CLASSROOM_CAPACITY
A 1 25
B 2 50
C 3 60
A 2 50
A 1 25 <--Not actually duplicate
Now you would say there are duplicate records. But in fact they are not duplicate in a way that there are some extra fields(not shown here) which would have different values for those seemingly duplicate records.
What I want:
SUBJ CLASSROOM CLASSROOM_CAPACITY
A 1 25
2 50
TOTAL 75
B 2 50
TOTAL 50
C 3 60
TOTAL 60
//EDIT - Apparently following line is causing too much confusion. Ignore it. How can I get rest of the table correctly?
TOTAL 135 //It seems its quite difficult to get 135 here. Its ok if this total is messed up
What I am trying:
SELECT
SOME_FIELDS,
SUBJ,
CLASSROOM,
SUM(CLASSROOM_CAPACITY)
FROM
MYTABLE
WHERE .....
GROUP BY SOME_FIELDS, ROLLUP(SUBJ,CLASSROOM)
The problem:
Thanks to those "seemingly duplicate" records, classroom capacities are being summed up multiple times. How do I prevent that? Am I doing this the wrong way?
The actual query is lot more complicated but I think if I can get this right, I can apply it to bigger query.
PS: I know how to get text "Total" instead of blank entry with ROLLUP using GROUPING so you can skip that part.
The cardinality you're introducing is a little off and when you sort the that ROLLUP starts to work. Your saying that:
SUBJ CLASSROOM CLASSROOM_CAPACITY
A 1 25
is equal to:
SUBJ CLASSROOM CLASSROOM_CAPACITY
A 1 25
But the SOME_FIELDS could vary per row. When you aggregate up to just the columns above, what do you expect to happen to SOME_FIELDS?
If these can be ignore for the purposes of this query your best bet is to first find the DISTINCT records (i.e. records that contain a unique tuple of subj, classroom and classroom_capacity) and then do the ROLLUP on this data set. The following query achieves this:
WITH distinct_subj_classrm_capacity AS (
SELECT DISTINCT
subj
, classroom
, classroom_capacity
FROM mytable
)
SELECT
subj
, classroom
, SUM(classroom_capacity)
FROM distinct_subj_classrm_capacity
GROUP BY ROLLUP(subj, classroom)
If you're not interested in the break report results that ROLLUP gives you and you simply want the raw totals then you can use the analytic version of SUM (see here for more on Oracle analytic functions: http://docs.oracle.com/cd/E11882_01/server.112/e26088/functions004.htm)
WITH distinct_subj_classrm_capacity AS (
SELECT DISTINCT
subj
, classroom
, classroom_capacity
FROM mytable
)
SELECT DISTINCT
subj
, SUM(classroom_capacity) OVER (PARTITION BY subj) classroom_capacity_per_subj
FROM distinct_subj_classrm_capacity
This gives results in the format:
SUBJ CLASSROOM_CAPACITY_PER_SUBJ
A 75
B 50
C 60
I have the following table (highscores),
id gameid userid name score date
1 38 2345 A 100 2009-07-23 16:45:01
2 39 2345 A 500 2009-07-20 16:45:01
3 31 2345 A 100 2009-07-20 16:45:01
4 38 2345 A 200 2009-10-20 16:45:01
5 38 2345 A 50 2009-07-20 16:45:01
6 32 2345 A 120 2009-07-20 16:45:01
7 32 2345 A 100 2009-07-20 16:45:01
Now in the above structure, a user can play a game multiple times but I want to display the "Games Played" by a specific user. So in games played section I can't display multiple games. So the concept should be like if a user played a game 3 times then the game with highest score should be displayed out of all.
I want result data like:
id gameid userid name score date
2 39 2345 A 500 2009-07-20 16:45:01
3 31 2345 A 100 2009-07-20 16:45:01
4 38 2345 A 200 2009-10-20 16:45:01
6 32 2345 A 120 2009-07-20 16:45:01
I tried following query but its not giving me the correct result:
SELECT id,
gameid,
userid,
date,
MAX(score) AS score
FROM highscores
WHERE userid='2345'
GROUP BY gameid
Please tell me what will be the query for this?
Thanks
Requirement is a bit vague/confusing but would something like this satisfy the need ?
(purposely added various aggregates that may be of interest).
SELECT gameid,
MIN(date) AS FirstTime,
MAX(date) AS LastTime,
MAX(score) AS TOPscore.
COUNT(*) AS NbOfTimesPlayed
FROM highscores
WHERE userid='2345'
GROUP BY gameid
-- ORDER BY COUNT(*) DESC -- for ex. to have games played most at top
Edit: New question about adding the id column to the the SELECT list
The short answer is: "No, id cannot be added, not within this particular construct". (Read further to see why) However, if the intent is to have the id of the game with the highest score, the query can be modified, using a sub-query, to achieve that.
As explained by Alex M on this page, all the column names referenced in the SELECT list and which are not used in the context of an aggregate function (MAX, MIN, AVG, COUNT and the like), MUST be included in the ORDER BY clause. The reason for this rule of the SQL language is simply that in gathering the info for the results list, SQL may encounter multiple values for such an column (listed in SELECT but not GROUP BY) and would then not know how to deal with it; rather than doing anything -possibly useful but possibly silly as well- with these extra rows/values, SQL standard dictates a error message, so that the user can modify the query and express explicitly his/her goals.
In our specific case, we could add the id in the SELECT and also add it in the GROUP BY list, but in doing so the grouping upon which the aggregation takes place would be different: the results list would include as many rows as we have id + gameid combinations the aggregate values for each of this row would be based on only the records from the table where the id and the gameid have the corresponding values (assuming id is the PK in table, we'd get a single row per aggregation, making the MAX() and such quite meaningless).
The way to include the id (and possibly other columns) corresponding to the game with the top score, is with a sub-query. The idea is that the subquery selects the game with TOP score (within a given group by), and the main query's SELECTs any column of this rows, even when the fieds wasn't (couldn't be) in the sub-query's group-by construct. BTW, do give credit on this page to rexem for showing this type of query first.
SELECT H.id,
H.gameid,
H.userid,
H.name,
H.score,
H.date
FROM highscores H
JOIN (
SELECT M.gameid, hs.userid, MAX(hs.score) MaxScoreByGameUser
FROM highscores H2
GROUP BY H2.gameid, H2.userid
) AS M
ON M.gameid = H.gameid
AND M.userid = H.userid
AND M.MaxScoreByGameUser = H.score
WHERE H.userid='2345'
A few important remarks about the query above
Duplicates: if there the user played several games that reached the same hi-score, the query will produce that many rows.
GROUP BY of the sub-query may need to change for different uses of the query. If rather than searching for the game's hi-score on a per user basis, we wanted the absolute hi-score, we would need to exclude userid from the GROUP BY (that's why I named the alias of the MAX with a long, explicit name)
The userid = '2345' may be added in the [now absent] WHERE clause of the sub-query, for efficiency purposes (unless MySQL's optimizer is very smart, currently all hi-scores for all game+user combinations get calculated, whereby we only need these for user '2345'); down side duplication; solution; variables.
There are several ways to deal with the issues mentioned above, but these seem to be out of scope for a [now rather lenghty] explanation about the GROUP BY constructs.
Every field you have in your SELECT (when a GROUP BY clause is present) must be either one of the fields in the GROUP BY clause, or else a group function such as MAX, SUM, AVG, etc. In your code, userid is technically violating that but in a pretty harmless fashion (you could make your code technically SQL standard compliant with a GROUP BY gameid, userid); fields id and date are in more serious violation - there will be many ids and dates within one GROUP BY set, and you're not telling how to make a single value out of that set (MySQL picks a more-or-less random ones, stricter SQL engines might more helpfully give you an error).
I know you want the id and date corresponding to the maximum score for a given grouping, but that's not explicit in your code. You'll need a subselect or a self-join to make it explicit!
Use:
SELECT t.id,
t.gameid,
t.userid,
t.name,
t.score,
t.date
FROM HIGHSCORES t
JOIN (SELECT hs.gameid,
hs.userid,
MAX(hs.score) 'max_score'
FROM HIGHSCORES hs
GROUP BY hs.gameid, hs.userid) mhs ON mhs.gameid = t.gameid
AND mhs.userid = t.userid
AND mhs.max_score = t.score
WHERE t.userid = '2345'