I have 2 tables:
Marks (studentnum,marks)
Student (SNum, SName)
if I do
Select SName, marks-avg(marks) from Marks join Student on SNum = studentnum
then I only get 1 row returned.
Is there a way to return all the list of students' names and the difference of the student's mark and the average (student's mark - average) without assigning a variable for average?
You're wanting to mix aggregate and non-aggregate values. This uses a subquery, but there might be other options depending on your server.
SELECT
SName,
marks - (SELECT avg(marks) FROM Marks as m2 WHERE m2.studentnum = m.studentnum)
FROM
Marks as m INNER JOIN
Student as s
ON s.SNum = m.studentnum
Try this:
Select s.sname, (m.mark - temp.avg)
From marks m
Inner join (select studentnum, avg(mark) as avg from marks group by studentnum) temp
On temp.studentnum = m.studentnum
Inner Join students s
On s.snum = m.studentnum
Related
In my query there is a value that will not match in the demand category table. Therefore, since one value does not match in the output of my query, other matching values do not appear.
I want to do;
How can I list other matching values even if there is an unmatched value in the query?
process Table
fk_unit_id fk_unit_position fk_demand_category
1 2 1
unit table
unit_id
1
unit_position table
unit_position
2
demand_category table
demand_category
1
Query:
SELECT unit_name,unit_position_name,demand_category_name From process
INNER JOIN unit ON process.fk_unit_id = unit_id and unit_id =1
INNER JOIN unit_position ON process.fk_unit_position_id = unit_position_id and unit_position_id = 2
INNER JOIN demand_category ON process.fk_demand_category_id = demand_category_id and demand_category_id =0 ;
Switch INNER JOIN on demand_category with LEFT JOIN
LEFT JOIN gets all records from the LEFT linked and the related record from the right table ,but if you have selected some columns from the RIGHT table, if there is no related records, these columns will contain NULL.
SELECT unit_name,unit_position_name,demand_category_name From process
INNER JOIN unit ON process.fk_unit_id = unit_id and unit_id =1
INNER JOIN unit_position ON process.fk_unit_position_id = unit_position_id and unit_position_id = 2
LEFT JOIN demand_category ON process.fk_demand_category_id = demand_category_id and demand_category_id =0 ;
You can use outer join to have the columns that don't match, just the corresponding values in other table will be padded with null. Other way is to use IN operator, but slower query performance.
I have the following query...
SELECT a.countryRegion, a.Stateprovince, SUM (soh.TotalDue) AS revenue,
CASE
WHEN GROUPING_ID(a.countryregion,a.stateprovince) = 0 THEN 'State/Province'
WHEN GROUPING_ID(a.countryregion,a.stateprovince) = 3 THEN 'Total'
WHEN GROUPING_ID(a.countryregion,a.stateprovince) = 1 THEN 'Country Total'
ELSE N'unknown'
END AS 'Level'
FROM saleslt.address AS a
JOIN saleslt.customeraddress AS ca
ON a.addressID = ca.addressID
JOIN saleslt.customer AS c
ON ca.customerID = c.customerID
JOIN salesLT.salesorderheader as soh
ON c.customerID = soh.customerID
GROUP BY ROLLUP(a.countryregion, a.stateprovince)
ORDER BY a.countryregion,a.stateprovince;
How do I get the row for Country to contain the value ‘United States Subtotal’, and the row for state/province to contain the value ‘California Subtotal’ for example?
The table includes about 8 distinct states/provinces and multiple countries.
Your, GROUP BY ROLLUP(a.countryregion, a.stateprovince) statement should return fields with NULL values before the sub-totals.
You can substitute these NULL values with "Sub Total:" by changing your select statement as follow:
SELECT
coalesce(a.countryRegion,"Sub Total:") as countryRegion,
coalesce(a.Stateprovince, "Sub Total:") as Stateprovince, .............
You can format your report output to get rid of repeated subtotals, or use a subquery to clean up repetition.
You can look at the LEAD() and LAG() Windowing Functions, to get the countryRegion and StateProvince from the previous line.
I have three data tables Employees, Departments, and Locations.
I want to show the total number of employees in each state and what percentage of the employees are located in that each state. The Employees table and the Departments table have one identical column called Department_ID, and the Departments table and the Locations table have one identical column called Location_ID. Here's what I wrote for my code:
select l.state_province e.count(*) as "Employees in State",
e.count(*)*100/sum(e.count(*)) over ()
from employees e
full outer join departments d on e.department_id = d.department_id
full outer join locations l on l.location_id = d.location_id
order by l.state_province;
However, the error "from keyword not found where expected" shows up when I run the code. How do I fix it?
You need group by. And regular joins should be fine:
select l.state_province, count(*) as "Employees in State",
count(*) * 100/sum(count(*)) over ()
from employees e join
departments d
on e.department_id = d.department_id join
locations l
on l.location_id = d.location_id
group by l.state_province
order by l.state_province;
I have a pretty simple chart with a likely common issue. I've searched for several hours on the interweb but only get so far in finding a similar situation.
the basics of what I'm pulling contains a created_by, person_id and risk score
the risk score can be:
1 VERY LOW
2 LOW
3 MODERATE STABLE
4 MODERATE AT RISK
5 HIGH
6 VERY HIGH
I want to get a headcount of persons at each risk score and display a risk count even if there is a count of 0 for that risk score but SSRS 2005 likes to suppress zero counts.
I've tried this in the point labels
=IIF(IsNothing(count(Fields!person_id.value)),0,count(Fields!person_id.value))
Ex: I'm missing values for "1 LOW" as the creator does not have any "1 LOW" they've assigned risk scores for.
*here's a screenshot of what I get but I'd like to have a column even for a count when it still doesn't exist in the returned results.
#Nathan
Example scenario:
select professor.name, grades.score, student.person_id
from student
inner join grades on student.person_id = grades.person_id
inner join professor on student.professor_id = professor.professor_id
where
student.professor_id = #professor
Not all students are necessarily in the grades table.
I have a =Count(Fields!person_id.Value) for my data points & series is grouped on =Fields!score.Value
If there were a bunch of A,B,D grades but no C & F's how would I show labels for potentially non-existent counts
In your example, the problem is that no results are returned for grades that are not linked to any students. To solve this ideally there would be a table in your source system which listed all the possible values of "score" (e.g. A - F) and you would join this into your query such that at least one row was returned for each possible value.
If such a table doesn't exist and the possible score values are known and static, then you could manually create a list of them in your query. In the example below I create a subquery that returns a combination of all professors and all possible scores (A - F) and then LEFT join this to the grades and students tables (left join means that the professor/score rows will be returned even if no students have those scores in the "grades" table).
SELECT
professor.name
, professorgrades.score
, student.person_id
FROM
(
SELECT professor_id, score
FROM professor
CROSS JOIN
(
SELECT 'A' AS score
UNION
SELECT 'B'
UNION
SELECT 'C'
UNION
SELECT 'D'
UNION
SELECT 'E'
UNION
SELECT 'F'
) availablegrades
) professorgrades
INNER JOIN professor ON professorgrades.professor_id = professor.professor_id
LEFT JOIN grades ON professorgrades.score = grades.score
LEFT JOIN student ON grades.person_id = student.person_id AND
professorgrades.professor_id = student.professor_id
WHERE professorgrades.professor_id = 1
See a live example of how this works here: SQLFIDDLE
SELECT RS.RiskScoreId, RS.Description, SUM(DT.RiskCount) AS RiskCount
FROM (
SELECT RiskScoreId, 1 AS RiskCount
FROM People
UNION ALL
SELECT RiskScoreId, 0 AS RiskCount
FROM RiskScores
) DT
INNER JOIN RiskScores RS ON RS.RiskScoreId = DT.RiskScoreId
GROUP BY RS.RiskScoreId, RS.Description
ORDER BY RS.RiskScoreId
I'm kind of rusty on my SQL, maybe you can help me out on this query.
I have these two tables for a tickets system (I'm omitting some fields):
table tickets
id - bigint
subject - text
user_id - bigint
closed - boolean
first_message - bigint
(foreign key, for next table's id)
last_message - bigint
(same as before)
table ticket_messages
creation_date
I need to query the closed tickets, and make an average of the time spent between the first message creation_date and the last message creation_date. This is what I've done so far:
SELECT t.id, t.subject, tm.creation_date
FROM tickets AS t
INNER JOIN ticket_messages AS tm
ON tm.id = t.first_message
OR tm.id = t.last_message
WHERE t.closed = true
I'm looking for some group by or aggregate function to get all the data from the table, and try to calculate the time spent between last and first, also trying to display the dates for the first and last message.
UPDATE I added an inner Join with the second table instead of "OR", now I get both dates, and I can find the sum from my application:
SELECT t.id, t.subject, tm.creation_date, tm2.creation_date
FROM tickets AS t
INNER JOIN ticket_messages AS tm
ON tm.id = t.first_message
INNER JOIN ticket_messages as tm2
ON tm2.id = t.last_message
WHERE t.closed = true
I think that did it...
Something like this should do for getting the nr of days elapsed. You might need to put this in a subquery to easily pull out more fields from 'tickets'.
SELECT t.id,AVG(tlast.creation_date - tfirst.creation_date)
FROM tickets AS t
INNER JOIN ticket_messages AS tfirst
ON tm.id = t.first_message
INNER JOIN ticket_messages AS tlast
ON tm.id = t.last_message
WHERE t.closed = true
GROUP BY t.id
Which might lead to(not tested..) e.g.
select t.id,t.subject,sub.nr_days
FROM (
SELECT t.id,AVG(tlast.creation_date - tfirst.creation_date) as nr_days
FROM tickets AS t
INNER JOIN ticket_messages AS tfirst
ON tm.id = t.first_message
INNER JOIN ticket_messages AS tlast
ON tm.id = t.last_message
WHERE t.closed = true
GROUP BY t.id ) AS sub
INNER JOIN tickets AS t
ON sub.id = t.id;
You are trying to combine two queries into one and trying to get the data from three rows of data from two tables. Both need to be fixed.
First of all, you should not attempt to mix aggregate data (such as averages) with the details for single items - you need separate queries for that. You can do it, but the output is repetitious and therefore wasteful (all the single items in a group will have the same aggregate data).
Secondly, you need to find the first message and the last message for a given ticket. Hence, that query is:
SELECT t.id, t.subject, tm1.creation_date as start, tm2.creation_date as end,
tm2.creation_date - tm1.creation_date as close_interval
FROM tickets AS t
INNER JOIN ticket_messages AS tm1 ON t.last_message = tm1.id
INNER JOIN ticket_messages AS tm2 ON t.last_message = tm2.id
WHERE t.closed = true
This gives you three rows of data per result row - as required. The computed value should be an interval type - assuming that PostgreSQL actually has that type. (In Informix, the type would effectively be INTERVAL DAY(n) for a suitable n, such as 9.)
You can average those intervals, now. You can't average dates because dates cannot be added together and cannot be divided; averaging involves both summing and dividing. Intervals can be added and divided.