I may have made the datascheme more complicated than i need to however this is the current data scheem and what im trying got accomplish.
Actor
id|name |website |...
1 |james |www.james.com |...
2 |ben |www.ben.com |...
Movie
id|name |poster|runtime...
1 |titanic |/a.jpg|98|
2 |Terminator|/b.jpg|77|
3 |MIB |/c.jpg|89|
Character
id|name
1 |tony
2 |bilbo
3 |gandalf
ActorMovieCharacterMapping
id|movie_id|actor_id|character_id
1 | 3 |5 |3
2 | 2 |5 |2
3 | 3 |2 |6
My goal is to get all of the Actors with their character name for a given movie in the fewest number of SQL queries as possible. I can get all of the actors in a movie or characters in a movie but dont know how to also retrieve that actors character name for that movie. Any help would be appreciated as well as possible ways to format these tables better.
Just do joins on mapping table:
select a.name as actor_name, c.name as character_nane
from ActorMovieCharacterMapping m
join Actor a on m.actor_id = a.id
join Movie mo on m.monie_id = mo.id
join Character c on m.character_id = c.id
where mo.id = 1
Related
Product table
|_id|name |
|---|------|
|3 |Laptop|
Size table
|_id|product_id|size|
|---|----------|----|
|5 |3 |15 |
|6 |3 |17 |
Query:
select tp._id, tp.name, ts.size from test_product tp
left join test_size ts on tp._id = ts.product_id
group by tp._id, tp.name, ts.size
where tp._id = 3 limit 10 offset 0
Current output:
|_id|name |size|
|---|------|----|
|3 |Laptop|15 |
|3 |Laptop|17 |
Expected output
|_id|name |size |
|---|------|-------|
|3 |Laptop|[15,17]|
Note:
Due to current query I'm getting 2 record for the same product and my limit and offset query logic is getting false and not getting proper count. I'm not well aware of Postgres queries for this kind of situation. So I need solution for this so my limit and offset logic will be correct for fetching data and for this query my count of product will be 1.
Use array_agg():
SELECT
tp._id,
tp.name,
ARRAY_AGG(ts.size ORDER BY ts.size) -- ORDER BY to get consistent results
FROM
test_product tp
LEFT JOIN test_size ts ON tp._id = ts.product_id
GROUP BY
tp._id,
tp.name
WHERE
tp._id = 3
LIMIT 10
OFFSET 0;
The ORDER BY within the aggregation is optional, but it's always nice to get consistent results over and over again.
I Have a query that finds a table, here's an example one.
Name |Age |Hair |Happy | Sad |
Jon | 15 | Black |NULL | NULL|
Kyle | 18 |Blonde |YES |NULL |
Brad | 17 | Blue |NULL |YES |
Name and age come from one table in a database, hair color comes from a second which is joined, and happy and sad come from a third table.My goal would be to make the first line of the chart like this:
Name |Age |Hair |Happy |Sad |
Jon | 15 |Black |Yes |Yes |
Basically I want to get rid of the rows under the first and get the non NULL data joined to the right. The problem is that there is no column where the Yes values are on the Jon row, so I have no idea how to get them there. Any suggestions?
PS. With the data I am using I can't just put a 'YES' in the 'Jon' row and call it a day, I would need to find the specific value from the lower rows and somehow get that value in the boxes that are NULL.
Do you just want COALESCE()?
COALESCE(Happy, 'Yes') as happy
COALESCE() replaces a NULL value with another value.
If you want to join on a NULL value work with nested selects. The inner select gets an Id for NULLs, the outer select joins
select COALESCE(x.Happy, yn_table.description) as happy, ...
from
(select
t1.Happy,
CASE WHEN t1.Happy is null THEN 1 END as happy_id
from t1 ...) x
left join yn_table
on x.xhappy_id = yn_table.id
If you apply an ORDER BY to the query, you can then select the first row relative to this order with WHERE rownum = 1. If you don't apply an ORDER BY, then the order is random.
After reading your new comment...
the sense is that in my real data the yes under the other names will be a number of a piece of equipment. I want the numbers of the equipment in one row instead of having like 8 rows with only 4 ' yes' values and the rest null.
... I come to the conclusion that this a XY problem.
You are asking about a detail you think will solve your problem, instead of explaining the problem and asking how to solve it.
If you want to store several pieces of equipment per person, you need three tables.
You need a Person table, an Article table and a junction table relating articles to persons to equip them. Let's call this table Equipment.
Person
------
PersonId (Primary Key)
Name
optional attributes like age, hair color
Article
-------
ArticleId (Primary Key)
Description
optional attributes like weight, color etc.
Equipment
---------
PersonId (Primary Key, Foreign Key to table Person)
ArticleId (Primary Key, Foreign Key to table Article)
Quantity (optional, if each person can have only one of each article, we don't need this)
Let's say we have
Person: PersonId | Name
1 | Jon
2 | Kyle
3 | Brad
Article: ArticleId | Description
1 | Hat
2 | Bottle
3 | Bag
4 | Camera
5 | Shoes
Equipment: PersonId | ArticleId | Quantity
1 | 1 | 1
1 | 4 | 1
1 | 5 | 1
2 | 3 | 2
2 | 4 | 1
Now Jon has a hat, a camera and shoes. Kyle has 2 bags and one camera. Brad has nothing.
You can query the persons and their equipment like this
SELECT
p.PersonId, p.Name, a.ArticleId, a.Description AS Equipment, e.Quantity
FROM
Person p
LEFT JOIN Equipment e
ON p.PersonId = e.PersonId
LEFT JOIN Article a
ON e.ArticleId = a.ArticleId
ORDER BY p.Name, a.Description
The result will be
PersonId | Name | ArticleId | Equipment | Quantity
---------+------+-----------+-----------+---------
3 | Brad | NULL | NULL | NULL
1 | Jon | 4 | Camera | 1
1 | Jon | 1 | Hat | 1
1 | Jon | 5 | Shoes | 1
2 | Kyle | 3 | Bag | 2
2 | Kyle | 4 | Camera | 1
See example: http://sqlfiddle.com/#!4/7e05d/2/0
Since you tagged the question with the oracle tag, you could just use NVL(), which allows you to specify a value that would replace a NULL value in the column you select from.
Assuming that you want the 1st row because it contains the smallest age:
- wrap your query inside a CTE
- in another CTE get the 1st row of the query
- in another CTE get the max values of Happy and Sad of your query (for your sample data they both are 'YES')
- cross join the last 2 CTEs.
with
cte as (
<your query here>
),
firstrow as (
select name, age, hair from cte
order by age
fetch first row only
),
maxs as (
select max(happy) happy, max(sad) sad
from cte
)
select f.*, m.*
from firstrow f cross join maxs m
You can try this:
SELECT A.Name,
A.Age,
B.Hair,
C.Happy,
C.Sad
FROM A
INNER JOIN B
ON A.Name = B.Name
INNER JOIN C
ON A.Name = B.Name
(Assuming that Name is the key columns in the 3 tables)
I am working on an application where I want to fetch the records from multiple tables which are connected through foreign key. The query I am using is
select ue.institute, ue.marks, uf.relation, uf.name
from user_education ue, user_family uf where ue.user_id=12 and uf.user_id=12
The result of the query is
You can see the data is repeating in it. I only want a record one time. I want no repetition. I want something like this
T1 T2
id|name|fid id|descrip| fid
1 |A |1 1|DA | 1
2 |B |1 2|DB | 1
2 |B |1
Result which I want:
Result:
id|name|fid|id|descrip| fid
1 |A |1 |1|DA | 1
2 |B |1 |2|DB | 1
2 |B |1 |
The results fetched through your query
The total rows are 5
More Information
I want the rows of same user_id from both tables but you can see in T1 there are 3 rows and in T2 there are 2 rows. I do not want repetitions but also I want to fetch all the data on the basis of user_id
Table Schemas,s
T1
T2
I can't see why you would want that, but the solution could be to use the window function row_number():
SELECT ue.institute, ue.marks, uf.relation, uf.name
FROM (SELECT institute, marks, row_number() OVER ()
FROM user_education
WHERE user_id=12) ue
FULL OUTER JOIN
(SELECT relation, name, row_number() OVER ()
FROM user_family
WHERE user_id=12) uf
USING (row_number);
The result would be pretty meaningless though, as there is no ordering defined in the individual result sets.
I have two tables with data like:
table: test_results
ID |test_id |test_type |result_1 |amps |volts |power |
----+-----------+-----------+-----------+-----------+-----------+-----------+
1 |101 |static |10.1 |5.9 |15 |59.1 |
2 |101 |dynamic |300.5 |9.1 |10 |40.1 |
3 |101 |prime |48.9 |8.2 |14 |49.2 |
4 |101 |dual |235.2 |2.9 |11 |25.8 |
5 |101 |static |11.9 |4.3 |9 |43.3 |
6 |101 |prime |49.9 |5.8 |15 |51.6 |
and
table: test_records
ID |model |test_date |operator |
----+-----------+-----------+-----------+
101 |m-300 |some_date |john doe |
102 |m-243 |some_date |john doe |
103 |m-007 |some_date |john doe |
104 |m-523 |some_date |john doe |
105 |m-842 |some_date |john doe |
106 |m-252 |some_date |john doe |
and I'm making a report that looks like this:
|static |dynamic |
test_id |model |test_date |operator |result_1 |amps |volts |power |result_1 |amps |volts |power |
-----------+-----------+-----------+-----------+-----------+-----------+-----------+-----------+-----------+-----------+-----------+-----------+
101 |m-300 |some_date |john doe |10.1 |5.9 |15 |59.1 |300.5 |9.1 |10 |40.1 |
with left outer joins like so:
SELECT
A.ID AS test_id, model, test_date, operator,
B.result_1, B.amps, B.volts, B.power,
C.result_1, C.amps, C.volts, C.power
FROM
test_records A
LEFT JOIN
test_results B
ON
A.ID = B.test_id
AND
B.test_type = 'static'
LEFT JOIN
test_results C
ON
A.ID = C.test_id
AND
C.test_type = 'dynamic'
But I have run into a problem. The "static" and "prime" tests are run twice.
I don't know how to differentiate between them to create their own 4 fields.
An abstracted(simplified) view of the desired report would look like:
|static |dynamic |prime |dual |static2 |prime2 |
|4 fields |4 fields |4 fields |4 fields |4 fields |4 fields |
Is this even possible?
Notes:
I'm labeling the groups of 4 fields with html so don't worry about the labels
Not every test will run "static" and "prime" twice. So this is a case of If ("static" and "prime") are found twice, do this SQL.
I think we're going to get our engineers to append a 2 to the second tests, eliminating the problem, so this question is more out of curiosity to know what method could solve a problem like this.
If you have another field (here I use ID) that you know is always going to be ordered in respect to the field you can use a windowing function to give them sequential values and then join to that. Like this:
WITH test_records_numbered AS
(
SELECT test_id, test_type, result_1, amps, volts, power,
ROW_NUMBER() OVER (PARTITION BY test_id, test_type ORDER BY ID) as type_num
FROM test_records
)
SELECT
A.ID AS test_id, model, test_date, operator,
B.result_1, B.amps, B.volts, B.power,
C.result_1, C.amps, C.volts, C.power
FROM test_records A
LEFT JOIN test_records_numbered B
ON A.ID = B.test_id AND B.test_type = 'static' and B.type_num = 1
LEFT JOIN test_records_numbered C
ON A.ID = C.test_id AND C.test_type = 'dynamic' and C.type_num = 2
I use a CTE to make it clearer but you could use a sub-queries, you would (of course) have to have the same sub-query twice in the SQL, most servers would have no issue optimizing without the CTE I expect.
I feel this solution is a bit of a "hack." You really want your original data to have all the information it needs. So I think it is good you are having your app developers modify their code (FWIW).
If this had to go into production I think I would break out the numbering as a view to hi-light the codification of questionable business rules (and to make it easy to change)
i have a table company row like this :
id(int) |name(string) |maincategory(int) |subcategory(string)
1 |Google |1 |1,2,3
2 |yahoo |4 |4,1
and other table category like:
id(int) |name(string)
1 |Search
2 |Email
3 |Image
4 |Video
i want to join tow table by company.subcategory = category.id
is it possible in sql ?
Start by splitting your subcategory column. In the end you should have an additional company_category table with company_id and category_id as columns.
company_id(int) |category_id(int)
1 |1
1 |2
1 |3
2 |4
2 |1
Your design is invalid. You shoud have another table called companySubcategories or something like that.
This table shoud have two columns companyId an categoryId.
Then your select would look like this:
select <desired fields> from
company c
join companySubcategories cs on cs.companyId = cs.id
join category ct on ct.id = cs.categoryId
you can do like below...
select * from
company c, category cc
where c. subcategory like '%'||cc.id||'%';
it is working as expected in oracle database ..
You could introduce a new table company_subcategory to keep track of subcategories
id (int) | subcategory(int)
1 | 1
1 | 2
1 | 3
2 | 1
2 | 4
then you would be able to run select as
select company.name AS company, category.name AS category
FROM company
JOIN company_subcategory
ON company.id = company_subcategory.company
JOIN category
ON company_subcategory.subcategory = category.id;
to get
+---------+----------+
| company | category |
+---------+----------+
| google | search |
| google | email |
| google | image |
| yahoo | search |
| yahoo | video |
+---------+----------+
SELECT *
FROM COMPANY CMP, CATEGORY CT
WHERE (SELECT CASE
WHEN INSTR(CMP.SUB_CATEGORY, CT.ID) > 0 THEN
'TRUE'
ELSE
'FALSE'
END
FROM DUAL) = 'TRUE'
This query looks for the ID in the SUB_CATEGORY, using the INSTR function.
In case it does exist, the row is returned.
The output is as below
ID NAME MAIN_CATEGORY SUB_CATEGORY ID NAME
1 Google 1 1,2,3 1 Search
1 Google 1 1,2,3 2 Email
1 Google 1 1,2,3 3 Image
2 yahoo 2 4,1 1 Search
2 yahoo 2 4,1 4 Video
Hope it helps.
However, I suggest you avoid this type of entries, as an ID should have separate entries and not combined entries. This may create problems in future, so it would be better to avoid it now.