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)
Related
I have a table like:
|------------------------|
|day name trees_planted|
|------------------------|
|1 | alice | 3 |
|2 | alice | 4 |
|1 | bob | 2 |
|2 | bob | 4 |
|------------------------|
I'm using SELECT name, SUM(trees_planted) FROM year2016 GROUP BY name to get:
name | trees_planted
alice | 7
bob | 6
But then I have another table from 2015 and I want to compare the results with the previous year, if for example Alice planted more trees in 2016 than in 2015 I'd get a result like this:
name | tree_difference
alice | -2 (if previous year she planted 5 trees, 5 -7 = -2)
bob | 0 (planted the same number of trees last year)
You could use a sub-query to get the records from both 2016 and 2015, but negate the values from 2016. Then group and sum like you already did:
SELECT name,
SUM(trees_planted) AS tree_difference
FROM (SELECT name, trees_planted
FROM year2015
UNION ALL
SELECT name, -trees_planted
FROM year2016
) AS years
GROUP BY name
This will also work for cases where a number is only given in one of the two years.
Assuming you can join using user field, you can do:
select a.name, a.tp, b.tp, a.tp - b.tp
from
(
(select name, SUM(trees_planted) tp from year2016 group by name) a
inner join
(select name, SUM(trees_planted) tp from year2015 group by name) b
using(name)
)
If you can't join on field user (you have different set of users in 2015 and 2016), it'll be easy to add the missing information by using a couple of union clauses.
Here's a link with artificial data to SQLFIDDLE to try the query.
I have a Family table:
SELECT * FROM Family;
id | Surname | Oldest | Oldest_Age
---+----------+--------+-------
1 | Byre | NULL | NULL
2 | Summers | NULL | NULL
3 | White | NULL | NULL
4 | Anders | NULL | NULL
The Family.Oldest column is not yet populated. There is another table of Children:
SELECT * FROM Children;
id | Name | Age | Family_FK
---+----------+------+--------
1 | Jake | 8 | 1
2 | Martin | 7 | 2
3 | Sarah | 10 | 1
4 | Tracy | 12 | 3
where many children (or no children) can be associated with one family. I would like to populate the Oldest column using an UPDATE ... SET ... statement that sets it to the Name and Oldest_Age of the oldest child in each family. Finding the name of each oldest child is a problem that is solved quite well here: How can I SELECT rows with MAX(Column value), DISTINCT by another column in SQL?
However, I don't know how to use the result of this in an UPDATE statement to update the column of an associated table using the h2 database.
The following is ANSI-SQL syntax that solves this problem:
update family
set oldest = (select name
from children c
where c.family_fk = f.id
order by age desc
fetch first 1 row only
)
In h2, I think you would use limit 1 instead of fetch first 1 row only.
EDIT:
For two columns -- alas -- the solution is two subqueries:
update family
set oldest = (select name
from children c
where c.family_fk = f.id
order by age desc
limit 1
),
oldest_age = (select age
from children c
where c.family_fk = f.id
order by age desc
limit 1
);
Some databases (such as SQL Server, Postgres, and Oracle) support lateral joins that can help with this. Also, row_number() can also help solve this problem. Unfortunately, H2 doesn't support this functionality.
I have an "insert only" database, wherein records aren't physically updated, but rather logically updated by adding a new record, with a CRUD value, carrying a larger sequence. In this case, the "seq" (sequence) column is more in line with what you may consider a primary key, but the "id" is the logical identifier for the record. In the example below,
This is the physical representation of the table:
seq id name | CRUD |
----|-----|--------|------|
1 | 10 | john | C |
2 | 10 | joe | U |
3 | 11 | kent | C |
4 | 12 | katie | C |
5 | 12 | sue | U |
6 | 13 | jill | C |
7 | 14 | bill | C |
This is the logical representation of the table, considering the "most recent" records:
seq id name | CRUD |
----|-----|--------|------|
2 | 10 | joe | U |
3 | 11 | kent | C |
5 | 12 | sue | U |
6 | 13 | jill | C |
7 | 14 | bill | C |
In order to, for instance, retrieve the most recent record for the person with id=12, I would currently do something like this:
SELECT
*
FROM
PEOPLE P
WHERE
P.ID = 12
AND
P.SEQ = (
SELECT
MAX(P1.SEQ)
FROM
PEOPLE P1
WHERE P.ID = 12
)
...and I would receive this row:
seq id name | CRUD |
----|-----|--------|------|
5 | 12 | sue | U |
What I'd rather do is something like this:
WITH
NEW_P
AS
(
--CTE representing all of the most recent records
--i.e. for any given id, the most recent sequence
)
SELECT
*
FROM
NEW_P P2
WHERE
P2.ID = 12
The first SQL example using the the subquery already works for us.
Question: How can I leverage a CTE to simplify our predicates when needing to leverage the "most recent" logical view of the table. In essence, I don't want to inline a subquery every single time I want to get at the most recent record. I'd rather define a CTE and leverage that in any subsequent predicate.
P.S. While I'm currently using DB2, I'm looking for a solution that is database agnostic.
This is a clear case for window (or OLAP) functions, which are supported by all modern SQL databases. For example:
WITH
ORD_P
AS
(
SELECT p.*, ROW_NUMBER() OVER ( PARTITION BY id ORDER BY seq DESC) rn
FROM people p
)
,
NEW_P
AS
(
SELECT * from ORD_P
WHERE rn = 1
)
SELECT
*
FROM
NEW_P P2
WHERE
P2.ID = 12
PS. Not tested. You may need to explicitly list all columns in the CTE clauses.
I guess you already put it together. First find the max seq associated with each id, then use that to join back to the main table:
WITH newp AS (
SELECT id, MAX(seq) AS latestseq
FROM people
GROUP BY id
)
SELECT p.*
FROM people p
JOIN newp n ON (n.latestseq = p.seq)
ORDER BY p.id
What you originally had would work, or moving the CTE into the "from" clause. Maybe you want to use a timestamp field rather than a sequence number for the ordering?
Following up from #Glenn's answer, here is an updated query which meets my original goal and is on par with #mustaccio's answer, but I'm still not sure what the performance (and other) implications of this approach vs the other are.
WITH
LATEST_PERSON_SEQS AS
(
SELECT
ID,
MAX(SEQ) AS LATEST_SEQ
FROM
PERSON
GROUP BY
ID
)
,
LATEST_PERSON AS
(
SELECT
P.*
FROM
PERSON P
JOIN
LATEST_PERSON_SEQS L
ON
(
L.LATEST_SEQ = P.SEQ)
)
SELECT
*
FROM
LATEST_PERSON L2
WHERE
L2.ID = 12
hopefully someone can help me with the following task:
I hVE got 2 tables Treatment and 'Person'. Treatment contains the dates when treatments for the different persons were started, Person contains personal information, e.g. lastname.
Now I have to find all persons where the duration between the first and last treatment is over 20 years.
The Tables look something like this:
Person
| PK_Person | First name | Name |
_________________________________
| 1 | A_Test | Karl |
| 2 | B_Test | Marie |
| 3 | C_Test | Steve |
| 4 | D_Test | Jack |
Treatment
| PK_Treatment | Description | Starting time | PK_Person |
_________________________________________________________
| 1 | A | 01.01.1989 | 1
| 2 | B | 02.11.2001 | 1
| 3 | A | 05.01.2004 | 1
| 4 | C | 01.09.2013 | 1
| 5 | B | 01.01.1999 | 2
So in this example, the output should be person Karl, A_Test.
Hopefully its understandable what the problem is and someone can help me.
Edit: There seems to be a problem with the formatting, the tables are not displayed correctly, I hope its readable.
SELECT *
FROM person p
INNER JOIN Treatment t on t.PK_Person = p.PK_Person
WHERE DATEDIFF(year,[TREATMENT_DATE_1], [TREATMENT_DATE_2]) > 20
This should do it, it is however untested so will need tweaking to your schema
Your data looks a bit suspicious, because the first name doesn't look like a first name.
But, what you want to do is aggregate the Treatment table for each person and get the minimum and maximum starting times. When the difference is greater than 20 years, then keep the person, and join back to the person table to get the names.
select p.FirstName, p.LastName
from Person p join
(select pk_person, MIN(StartingTime) as minst, MAX(StartingTime) as maxst
from Treatment t
group by pk_person
having MAX(StartingTime) - MIN(StartingTime) > 20*365.25
) t
on p.pk_person = t.pk_person;
Note that date arithmetic does vary between databases. In most databases, taking the difference of two dates counts the number of days between them, so this is a pretty general approach (although not guaranteed to work on all databases).
I've taken a slightly different approach and worked with SQL Fiddle to verify that the below statements work.
As mentioned previously, the data does seem a bit suspicious; nonetheless per your requirements, you would be able to do the following:
select P.PK_Person, p.FirstName, p.Name
from person P
inner join treatment T on T.pk_person = P.pk_person
where DATEDIFF((select x.startingtime from treatment x where x.pk_person = p.pk_person order by startingtime desc limit 1), T.StartingTime) > 7305
First, we need to inner join treatements which will ignore any persons who are not in the treatment table. The where portion now just needs to select based on your criteria (in this case a difference of dates). Doing a subquery will generate the last date a person has been treated, compare that to each of your records, and filter by number of days (7305 = 20 years * 365.25).
Here is the working SQL Fiddle sample.
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.