Basically, I have 3 tables, titles, providers, and provider_titles.
Let's say they look like this:
| title_id | title_name |
|------------|----------------|
| 1 | San Andres |
| 2 |Human Centipede |
| 3 | Zoolander 2 |
| 4 | Hot Pursuit |
| provider_id| provider_name |
|------------|----------------|
| 1 | Hulu |
| 2 | Netflix |
| 3 | Amazon_Prime |
| 4 | HBO_GO |
| provider_id| title_id |
|------------|----------------|
| 1 | 1 |
| 1 | 2 |
| 2 | 1 |
| 3 | 1 |
| 3 | 3 |
| 4 | 4 |
So, clearly there are titles with multiple providers, yeah? Typical many-to-many so far.
So what I'm doing to query it is with a JOIN like the following:
SELECT * FROM provider_title JOIN provider ON provider_title.provider_id = provider.provider_id JOIN title ON title.title_id = provider_title.title_id WHERE provider.name IN ('Netflix', 'HBO_GO', 'Hulu', 'Amazon_Prime')
Ok, now to the actual issue. I don't want repeated title names back, but I do want all of the providers associated with the title. Let me explain with another table. Here is what I am getting back with the current query, as is:
| provider_id| provider_name | title_id | title_name |
|------------|---------------|----------|---------------|
| 1 | Hulu | 1|San Andreas |
| 1 | Hulu | 2|Human Centipede|
| 2 | Netflix | 1|San Andreas |
| 3 | Amazon_Prime | 1|San Andreas |
| 3 | Amazon_prime | 3|Zoolander 2 |
| 4 | HBO_GO | 4|Hot Pursuit |
But what I really want would be something more like
| provider_id| provider_name |title_id| title_name|
|------------|-----------------------------|--------|-----------|
| [1, 2, 3] |[Hulu, Netflix, Amazon_Prime]| 1|San Andreas|
Meaning I only want distinct titles back, but I still want each title's associated providers. Is this only possible to do post-sql query with logic iterating through the returned rows?
Depending on your database engine, there may be an aggregation function to help achieve this.
For example, this SQLfiddle demonstrates the postgres array_agg function:
SELECT t.title_id,
t.title_name,
array_agg( p.provider_id ),
array_agg( p.provider_name )
FROM provider_title as pt
JOIN
provider as p
ON pt.provider_id = p.provider_id
JOIN title as t
ON t.title_id = pt.title_id
GROUP BY t.title_id,
t.title_name
Other database engines have equivalents. For example:
mySQL has group_concat
Oracle has listagg
sqlite has group_concat (as well!)
If your database isn't covered by the above, you can google '[Your database engine] aggregate comma delimited string'
Related
I am very new to database design and am using MS Access to try achieve my task. I am trying to create a database design that will allow for the name and description of two items to be queried
on a single row of information. Here is the problem: certain items are converted to other particular items -
any item can have multiple conversions performed on it, and all conversions will have two (many) items involved.
In this sense, we have a many-to-many relationship which necessitates the use of an intermediate table. My
tables must be structured in a way that allows for me to, in one row, query the Item ID's and names
of which items were involved in conversions.
My current table layout is as follows:
Items
+--------+----------+------------------+--+
| ItemID*| ItemName | ItemDescription | |
+--------+----------+------------------+--+
| 1 | DESK | WOOD, 4 LEG | |
| 2 | SHELF | WOOD, SOLID BASE | |
| 3 | TABLE | WOOD, 4 LEG | |
+--------+----------+------------------+--+
ItemConversions
+------------------+--------------+
| ConversionID(CK) | Item1_ID(CK) |
+------------------+--------------+
| 1 | 2 |
| 2 | 2 |
| 3 | 1 |
+------------------+--------------+
Conversions
+---------------+----------+----------+
| ConversionID* | Item1_ID | Item2_ID |
+---------------+----------+----------+
| 1 | 2 | 1 |
| 2 | 2 | 3 |
| 3 | 1 | 3 |
+---------------+----------+----------+
What I want is for it to be possible to achieve the kind of query I described above, though I don't think
my current layout is going to work for this, since the tables are only being joined on Item1_ID. Any advice
would be appreciated, hopefully my tables are not too specific and this is easily understandable.
A sample query output might look like this:
+--------------+----------+----------+----------+----------+
| ConversionID | Item1_ID | ItemName | Item2_ID | ItemName |
+--------------+----------+----------+----------+----------+
| 1 | 2 | SHELF | 1 | DESK |
+--------------+----------+----------+----------+----------+
I got it working how I wanted to with the help of June7's suggestion - I didn't know you could add in tables
multiple times in the query design page (very useful!). As for the tables, I edited the layout so that I have only
Items and Conversions (I deleted ItemConversions). Using the AS sql command I was able to write a query that pulls
the data I want from the tables. The table and query layout can be seen below:
Items
+--------+----------+------------------+--+
| ItemID*| ItemName | ItemDescription | |
+--------+----------+------------------+--+
| 1 | DESK | WOOD, 4 LEG | |
| 2 | SHELF | WOOD, SOLID BASE | |
| 3 | TABLE | WOOD, 4 LEG | |
+--------+----------+------------------+--+
Conversions
+---------------+----------+----------+
| ConversionID* | Item1_ID | Item2_ID |
+---------------+----------+----------+
| 1 | 2 | 1 |
| 2 | 2 | 3 |
| 3 | 3 | 1 |
+---------------+----------+----------+
Query:
SELECT
Conversions.ConversionID,
Conversions.Item1_ID,
Conversions.Item2_ID,
Items.ItemName,
Items_1.ItemName,
FROM
(
Conversions
INNER JOIN
Items
ON Conversions.Item1_ID = Items.ItemID
)
INNER JOIN
Items AS Items_1
ON Conversions.Item2_ID = Items_1.ItemID;
I have the following data:
select * from art_skills_table;
+----+------+---------------------------+
| ID | Name | skills |
+----+------+---------------------------|
| 1 | Anna | ["painting","photography"]|
| 2 | Bob | ["drawing","sculpting"] |
| 3 | Cat | ["pastel"] |
+----+------+---------------------------+
select * from computer_table;
+------+------+-------------------------+
| ID | Name | skills |
+------+------+-------------------------+
| 1 | Anna | ["word","typing"] |
| 2 | Cat | ["code","editing"] |
| 3 | Bob | ["excel","code"] |
+------+------+-------------------------+
I would like to write an SQL statement which results in the following table.
+------+------+-----------------------------------------------+
| ID | Name | skills |
+------+------+-----------------------------------------------+
| 1 | Anna | ["painting","photography","word","typing"] |
| 2 | Bob | ["drawing","sculpting","excel","code"] |
| 3 | Cat | ["pastel","code","editing"] |
+------+------+-----------------------------------------------+
I've tried something like SELECT * from art_skills_table LEFT JOIN computer_table ON name. However it doesn't give what I need. I've read about array_cat but I'm having a bit of trouble implementing it.
if the skills column from both tables are arrays, then you should be able to get away with this:
SELECT a.ID, a.name, array_cat(a.skills, c.skills)
FROM art_skills_table a LEFT JOIN computer_table c
ON c.id = a.id
That said, While you used LEFT join in your sample, I think either an INNER or FULL (OUTER) join might serve you better.
First, i wondered why the data are stored in such a model.
Was of the opinion that NoSQL databases lack ability for joins and ...
... a semantic triple would be in the form of subject–predicate–object.
... a Key-value (KV) stores use associative arrays.
... a relational database would be normalized.
A few information about the use case would have helped.
Nevertheless, you can select the data with CONCAT and REPLACE for the desired form.
SELECT art_skills_table.ID, computer_table.name,
CONCAT(
REPLACE(art_skills_table.skills, '}',','),
REPLACE(computer_table.skills, '{','')
)
FROM art_skills_table JOIN computer_table ON art_skills_table.ID = computer_table.ID
The query returns the following result:
+----+------+--------------------------------------------+
| ID | Name | Skills |
+----+------+--------------------------------------------+
| 1 | Anna | {"painting","photography","word","typing"} |
| 2 | Cat | {"drawing","sculpting","code","editing"} |
| 3 | Bob | {"pastel","excel","code"} |
+----+------+--------------------------------------------+
I've used the ID for the JOIN, even though Bob has different values.
The JOIN should probably be done over the name.
JOIN computer_table ON art_skills_table.Name = computer_table.Name
BTW, you need to tell us what SQL engine you're running on.
I have a database table that has a companion many-to-many self-join table alongside it. The primary table is part and the other table is alternate_part (basically, alternate parts are identical to their main part with different #s). Every record in the alternate_part table is also in the part table. To illustrate:
`part`
| part_id | part_number | description |
|---------|-------------|-------------|
| 1 | 00001 | wheel |
| 2 | 00002 | tire |
| 3 | 00003 | window |
| 4 | 00004 | seat |
| 5 | 00005 | wheel |
| 6 | 00006 | tire |
| 7 | 00007 | window |
| 8 | 00008 | seat |
| 9 | 00009 | wheel |
| 10 | 00010 | tire |
| 11 | 00011 | window |
| 12 | 00012 | seat |
`alternate_part`
| main_part_id | alt_part_id |
|--------------|-------------|
| 1 | 5 | // Wheel
| 5 | 1 | // |
| 5 | 9 | // |
| 9 | 5 | // |
| 2 | 6 | // Tire
| 6 | 2 | // |
| ... | ... | // |
I am trying to produce a simple SQL query that will give me a list of all alternates for a main part. The tricky part is: some alternates are only listed as alternates of alternates, it is not guaranteed that every viable alternate for a part is listed as a direct alternate. e.g., if 'Part 3' is an alternate of 'Part 2' which is an alternate of 'Part 1', then Part 3 is an alternate of Part 1 (even if the alternate_part table doesn't list a direct link). The reverse is also true (Part 1 is an alternate of Part 3).
Basically, right now I'm pulling alternates and iterating through them
SELECT p.*, ap.*
FROM part p
INNER JOIN alternate_part ap ON p.part_id = ap.main_part_id
And then going back and doing the same again on those alternates. But, I think there's got to be a better way.
The SQL query I'm looking for will basically give me:
| part_id | alt_part_id |
|---------|-------------|
| 1 | 5 |
| 1 | 9 |
For part_id = 1, even when 1 & 9 are not explicitly linked in the alternates table.
Note: I have no control whatever over the structure of the DB, it is a distributed software solution.
Note 2: It is an Oracle platform, if that affects syntax.
You have to create hierarchical tree , probably you have to use connect by prior , nocycle query
something like this
select distinct p.part_id,p.part_number,p.description,c.main_part_id
from part p
left join (
select main_part_id,connect_by_root(main_part_id) real_part_id
from alternate_part
connect by NOCYCLE prior main_part_id = alternate_part_id
) c
on p.part_id = c.real_part_id and p.part_id != c.main_part_id
order by p.part_id
You can read full documentation about Hierarchical queries at http://docs.oracle.com/cd/B28359_01/server.111/b28286/queries003.htm
I have tables with information similar to the following:
Table A is a list of circuits:
Circuit | CktType | CktSize
--------------------------------
CKT1 | ABC123 | 10
CKT2 | ABC123 | 12
CKT3 | XYZ789 | 10
Table B is a list of Raceway:
Raceway | RwyType | RwySize
--------------------------------
RWY1 | C | 4
RWY2 | T | 4x6
RWY3 | T | 8x12
Table C is a list of how the circuits go through the Raceway:
Circuit | Sequence | Raceway
--------------------------------
CKT1 | 1 | RWY1
CKT1 | 2 | RWY2
CKT1 | 3 | RWY3
CKT2 | 1 | RWY2
Table C may or may not have entries for all items in tables A and B. There is not a set number or a maximum number of entries in table C for each item in tables A and B.
I would like to write 2 queries in Oracle to retrieve the following data (clearly the queries would be very similar so only really looking for help writing one of them).
All Circuit information with the raceways the circuit goes through
Results Desired:
Circuit | CktType | CktSize | Raceway
----------------------------------------------
CKT1 | ABC123 | 10 | RWY1, RWY2, RWY3
CKT2 | ABC123 | 12 | RWY2
CKT3 | XYZ789 | 10 | (null)
All Raceway information with the circuits in the raceway:
Results Desired:
Raceway | RwyType | RwySize | Circuit
----------------------------------------------
RWY1 | C | 4 | CKT1
RWY2 | T | 4x6 | CKT1, CKT2
RWY3 | T | 8x12 | CKT1
Thanks in advance.
This would be one of your two queries. That produces each circuit information and against it the Raceway sequence separated by commas.. check it out.
SELECT Circuit,
CktType,
CktSize,
RTRIM (
XMLAGG (XMLELEMENT (e, Raceway || ', ') ORDER BY Sequence).EXTRACT (
'//text()'),
', ')
Raceways
FROM (SELECT t_A.Circuit,
t_A.CktType,
t_A.CktSize,
t_C.Raceway,
t_c.Sequence
FROM tableA t_A
LEFT OUTER JOIN
tableC t_C
ON t_A.Circuit = t_C.Circuit)
GROUP BY Circuit;
EDIT: After re-reading your post, I realized this would not work for you. Try the "For XML PATH".
Here is a great example: sql-query-concatenating-results-into-one-string
I'm sure this has been asked but I can't quite find the right search terms.
Given a schema like this:
| CarMakeID | CarMake
------------------------
| 1 | SuperCars
| 2 | MehCars
| CarMakeID | CarModelID | CarModel
-----------------------------------------
| 1 | 1 | Zoom
| 2 | 1 | Wow
| 3 | 1 | Awesome
| 4 | 2 | Mediocrity
| 5 | 2 | YoureSettling
I want to produce a dataset like this:
| CarMakeID | CarMake | CarModels
---------------------------------------------
| 1 | SuperCars | Zoom, Wow, Awesome
| 2 | MehCars | Mediocrity, YoureSettling
What do I do in place of 'AGG' for strings in SQL Server in the following style query?
SELECT *,
(SELECT AGG(CarModel)
FROM CarModels model
WHERE model.CarMakeID = make.CarMakeID
GROUP BY make.CarMakeID) as CarMakes
FROM CarMakes make
http://www.simple-talk.com/sql/t-sql-programming/concatenating-row-values-in-transact-sql/
It is an interesting problem in Transact SQL, for which there are a number of solutions and considerable debate. How do you go about producing a summary result in which a distinguishing column from each row in each particular category is listed in a 'aggregate' column? A simple, and intuitive way of displaying data is surprisingly difficult to achieve. Anith Sen gives a summary of different ways, and offers words of caution over the one you choose...
If it is SQL Server 2017 or SQL Server VNext, Azure SQL database you can use String_agg as below:
SELECT make.CarMakeId, make.CarMake,
CarModels = string_agg(model.CarModel, ', ')
FROM CarModels model
INNER JOIN CarMakes make
ON model.CarMakeId = make.CarMakeId
GROUP BY make.CarMakeId, make.CarMake
Output:
+-----------+-----------+---------------------------+
| CarMakeId | CarMake | CarModels |
+-----------+-----------+---------------------------+
| 1 | SuperCars | Zoom, Wow, Awesome |
| 2 | MehCars | Mediocrity, YoureSettling |
+-----------+-----------+---------------------------+