I'm trying to list result from a multi-table query with on row, 2 columns. I have the correct data that I need, I merely need to trim it down to 1 line of results. In other words, eliminate duplicate entries in the result. I'm using a value not shown here, school_id. Should I go with that as a distinct value? Can I do that without displaying the school_id?
SQL> select DISTINCT(school_name),Team_Name
2 from school, team
3 where team.team_name like '%B%'
4 AND school.school_id = team.school_id;
SCHOOL_NAME TEAM_NAME
-------------------------------------------------- ----------
Lawrence Central High School Bears
Lawrence Central High School BEars
Lawrence Central High School BEARS
The problem, as I'm sure you know, is the fact that "Bears" is in 3 different cases here. The simple fix is to do the upper or lower of "Team_Name" so it will only have 1 return record.
UPPER(Team_Name)
Related
This has been driving me and my team up the wall. I cannot compose a query that will strict match a single record that has a specific permutation of look ups.
We have a single lookup table
room_member_lookup:
room | member
---------------
A | Michael
A | Josh
A | Kyle
B | Kyle
B | Monica
C | Michael
I need to match a room with an exact list of members but everything else I've tried on stack overflow will still match room A even if I ask for a room with ONLY Josh and Kyle
I've tried queries like
SELECT room FROM room_member_lookup
WHERE member IN (Josh, Michael)
GROUP BY room
HAVING COUNT(1) = 2
However this will still return room A even though that has 3 members I need a exact member permutation and that matches the room even not partials.
SELECT room
FROM room_member_lookup a
WHERE member IN ('Monica', 'Kyle')
-- Make sure that the room 'a' has exactly two members
and (select count(*)
from room_member_lookup b
where a.room=b.room)=2
GROUP BY room
-- and both members are in that room
HAVING COUNT(1) = 2
Depending on the SQL dialect, one can build a dynamic table (CTE or select .. union all) to hold the member set (Monica and Kyle, for example), and then look for set equivalence using MINUS/EXCEPT sql operators.
I'm trying to find the match no in which Germany played against Poland. This is from https://www.w3resource.com/sql-exercises/soccer-database-exercise/sql-subqueries-exercise-soccer-database-4.php. There are two tables : match_details and soccer_country. I don't understand how the count(distinct) works in this case. Can someone please clarify? Thanks!
SELECT match_no
FROM match_details
WHERE team_id = (
SELECT country_id
FROM soccer_country
WHERE country_name = 'Germany')
OR team_id = (
SELECT country_id
FROM soccer_country
WHERE country_name = 'Poland')
GROUP BY match_no
HAVING COUNT(DISTINCT team_id) = 2;
As Lamak mentioned, what an ugly consideration for a query, but many ways to approach a query.
As mentioned, counting for (Distinct team_id) makes sure that there are only 2 unique teams. If there is ever a Cartesian result, you could get repetition of multiple rows showing more than one instance of both teams. So the count of distinct on the TEAM_ID eliminates that.
Now, that said, Other "team" query data structures I have seen have a single record for the match and a column for EACH TEAM playing the match. That is easier by a long-shot, but still a relatively easy query.
Break the query down a little, and consider a large scale set of data (not that this, or any sort of even professional league would have such large record counts to give delay with a sql engine).
Your first criteria is games with Germany. So lets start with that.
SELECT
md1.match_no
FROM
match_details md1
JOIN soccer_country sc1
on md1.team_id = sc1.country_id
AND sc1.country_name = 'Germany'
So, why even look at any other record/match if Germany is not even part of the match on either side. Of which this in itself would return 6 matches from the sample data of 51 matches. So now, all you need to do is join AGAIN to the match details table a second time for only those matches, but ALSO the second team is Poland
SELECT
md1.match_no
FROM
match_details md1
JOIN soccer_country sc1
on md1.team_id = sc1.country_id
AND sc1.country_name = 'Germany'
-- joining again for the same match Germany was already qualified
JOIN match_details md2
on md1.match_no = md2.match_no
-- but we want the OTHER team record since Germany was first team
and md1.team_id != md2.team_id
-- and on to the second country table based on the SECOND team ID
JOIN soccer_country sc2
on md2.team_id = sc2.country_id
-- and the second team was Poland
AND sc2.country_name = 'Poland'
Yes, may be a longer query, but by eliminating 45 other matches (again, thinking a LARGE database), you have already saved blowing through tons of data to a very finite set. And now finishing only those Germany / Poland. No aggregates, counts, distincts, just direct joins.
FEEDBACK
Lets take a look at some BAD sample data... which as all programmers know, there is no such thing (NOT). Anyhow, lets take a look at these few matches.
Match Team ID blah
52 Poland Just put the names here for simplistic purposes
52 Poland
53 Germany
53 Germany
If you were to run the query without DISTINCT Teams, both match 52 and 53 would show up... As Poland is one team and appears 2 times for match 52, and similarly Germany 2 times for match 53. By doing DISTINCT Team, you can see that for each match, there is only 1 team being returned and thus excluded. Does that help? Again, no such thing as bad data :)
And yet another sample match where more than 2 teams created
Match Team ID
54 France
54 Poland
54 England
55 Hungary
56 Austria
In each of these matches, NONE would be returned. Match 54 has 3 distinct teams, and Match 55 and 56 only have single entry, thus no opponent to compete against.
2nd FEEDBACK
To clarify the query. If you look at the short query for just Germany, that aliased instance of "md1" is already sitting on any given record for a Germany match. So the second join to the "md2", I only care about the same match, so I can join on the same match_no. However, in the "md2" alias, the "!=" means NOT EQUAL. ! = logical NOT. So the join is saying from the MD1, join to the MD2 alias on the same match id. However, only give me where the teams are NOT the same. So the first instance holds Germany's team ID (already qualified) and thus give me the secondary team id. So now I can use the secondary (md2) instance team ID to join to the country to confirm only for Poland.
Does this now clarify things for you?
I am trying to work with two tables on BigQuery. From table1 I want to find the accession ID of all records that are "World", and then from each of those accession numbers I want to create a column with every name in a separate row. Unfortunately, when I run this:
Select name
From `table2`
Where acc IN (Select acc
From `table1`
WHERE source = 'World')
Instead of getting something like this:
Acc1
Acc2
Acc3
Jeff
Jeff
Ted
Chris
Ted
Blake
Rob
Jack
Jack
I get something more like this:
row
name
1
Jeff
2
Chris
3
Rob
4
Jack
5
Jeff
6
Jack
7
Ted
8
Blake
Ultimately, I am hoping to download the data and somehow use python or something to take each name and count the number of times it shows up with each other name at a given accession number, and furthermore measure the degree to which each pairing is also found with third names in any given column, i.e. the degree to which they share a cohort. So I need to preserve the groupings which exist with each accession number, but I am struggling to find info on how one might do this.
Could anybody point me in the right direct for this, or otherwise is the way I am going about this wise if that is my end goal?
Thanks!
This is not a direct answer to the question you asked. In general, it is easier to handle multiple rows rather than multiple columns.
So, I would recommend that you put each acc value in a separate row and then list the names as an array:
select t2.acc, array_agg(t2.name order by t2.name) as names
from `table2` t2
where t2.acc in (Select t1.acc
From `table1` t1
where t1.source = 'World'
)
group by t2.acc;
Otherwise, you are going to have a challenge just naming the columns in your result set.
Due to the way a particular table is written I need to do something a little strange in SQL and I can't find a 'simple' way to do this
Table
Name Place Amount
Chris Scotland
Chris £1
Amy England
Amy £5
Output
Chris Scotland £1
Amy England £5
What I am trying to do is above, so the null rows are essentially ignored and 'grouped' up based on the Name
I have this working using For XML however it is incredibly slow, is there a smarter way to do this?
This is where MAX would work
select
Name
,Place = Max(Place)
,Amount = Max(Amount)
from
YourTable
group by
Name
Naturally, if you have more than one occurance of a place for a given name, you may get unexpected results.
Being new with SQL and SSRS and can do many things already, but I think I must be missing some basics and therefore bang my head on the wall all the time.
A report that is almost working, needs to have more results in it, based on conditions.
My working query so far is like this:
SELECT projects.project_number, project_phases.project_phase_id, project_phases.project_phase_number, project_phases.project_phase_header, project_phase_expensegroups.projectphase_expense_total, invoicerows.invoicerow_total
FROM projects INNER JOIN
project_phases ON projects.project_id = project_phases.project_id
LEFT OUTER JOIN
project_phase_expensegroups ON project_phases.project_phase_id = project_phase_expensegroups.project_phase_id
LEFT OUTER JOIN
invoicerows ON project_phases.project_phase_id = invoicerows.project_phase_id
WHERE ( projects.project_number = #iProjectNumber )
AND
( project_phase_expensegroups.projectphase_expense_total >0 )
The parameter is for selectionlist that is used to choose a project to the report.
How to have also records that have
( project_phase_expensegroups.projectphase_expense_total ) with value 0 but there might be invoices for that project phase?
Tried already to add another condition like this:
WHERE ( projects.project_number = #iProjectNumber )
AND
( project_phase_expensegroups.projectphase_expense_total > 0 )
OR
( invoicerows.invoicerow_total > 0 )
but while it gives some results - also the one with projectphase_expense_total with value 0, but the report is total mess.
So my question is: what am I doing wrong here?
There is a core problem with your query in that you are left joining to two tables, implying that rows may not exist, but then putting conditions on those tables, which will eliminate NULLs. That means your query is internally inconsistent as is.
The next problem is that you're joining two tables to project_phases that both may have multiple rows. Since these data are not related to each other (as proven by the fact that you have no join condition between project_phase_expensegroups and invoicerows, your query is not going to work correctly. For example, given a list of people, a list of those people's favorite foods, and a list of their favorite colors like so:
People
Person
------
Joe
Mary
FavoriteFoods
Person Food
------ ---------
Joe Broccoli
Joe Bananas
Mary Chocolate
Mary Cake
FavoriteColors
Person Color
------ ----------
Joe Red
Joe Blue
Mary Periwinkle
Mary Fuchsia
When you join these with links between Person <-> Food and Person <-> Color, you'll get a result like this:
Person Food Color
------ --------- ----------
Joe Broccoli Red
Joe Bananas Red
Joe Broccoli Blue
Joe Bananas Blue
Mary Chocolate Periwinkle
Mary Chocolate Fuchsia
Mary Cake Periwinkle
Mary Cake Fuchsia
This is essentially a cross-join, also known as a Cartesian product, between the Foods and the Colors, because they have a many-to-one relationship with each person, but no relationship with each other.
There are a few ways to deal with this in the report.
Create ExpenseGroup and InvoiceRow subreports, that are called from the main report by a combination of project_id and project_phase_id parameters.
Summarize one or the other set of data into a single value. For example, you could sum the invoice rows. Or, you could concatenate the expense groups into a single string separated by commas.
Some notes:
Please, please format your query before posting it in a question. It is almost impossible to read when not formatted. It seems pretty clear that you're using a GUI to create the query, but do us the favor of not having to format it ourselves just to help you
While formatting, please use aliases, Don't use full table names. It just makes the query that much harder to understand.
You need an extra parentheses in your where clause in order to get the logic right.
WHERE ( projects.project_number = #iProjectNumber )
AND (
(project_phase_expensegroups.projectphase_expense_total > 0)
OR
(invoicerows.invoicerow_total > 0)
)
Also, you're using a column in your WHERE clause from a table that is left joined without checking for NULLs. That basically makes it a (slow) inner join. If you want to include rows that don't match from that table you also need to check for NULL. Any other comparison besides IS NULL will always be false for NULL values. See this page for more information about SQL's three value predicate logic: http://www.firstsql.com/idefend3.htm
To keep your LEFT JOINs working as you intended you would need to do this:
WHERE ( projects.project_number = #iProjectNumber )
AND (
project_phase_expensegroups.projectphase_expense_total > 0
OR project_phase_expensegroups.project_phase_id IS NULL
OR invoicerows.invoicerow_total > 0
OR invoicerows.project_phase_id IS NULL
)
I found the solution and it was kind easy after all. I changed the only the second LEFT OUTER JOIN to INNER JOIN and left away condition where the query got only results over zero. Also I used SELECT DISTINCT
Now my report is working perfectly.