I have a problem and I hope you can guide me, I have 3 tables in sql server with the following characteristics:
Table Invoice
ID Folio
------------------
1 101010
2 202020
Table Additional
ID Name
--------------------------
1 Order Number
2 Branch
Table AdditionalInvoice:
ID_INVOICE ID_ADDITIONAL VALUE
------------------------------------------------------------
1 1 1234/1
1 2 NORTH
2 1 5678/9
2 2 SOUTH
The table 3 depends on table 1 and 2 and the ratio is one to many, I look for the following result:
Query results
ID Folio Order Number Branch
------------------------------------------------------------
1 101010 1234/1 NORTH
2 202020 5678/9 SOUTH
Investigating I can use PIVOT or CROSS APPLY, but I find myself a little lost :( or someone who has another solution to the problem of dynamic columns?
While this can be done with PIVOT and/or CROSS APPLY, I would just use conditional aggregation, which is an efficient and cross-database solution:
select
i.id,
i.folio,
max(case when a.name = 'Order Number' then ai.value end) OrderNumber,
max(case when a.name = 'Branch' then ai.value end) Branch
from Invoice i
inner join AdditionalInvoice ai on ai.id_invoice = i.id
inner join Additional a on a.id = ai.id_additional
group by i.id, i.folio
Note: rereading your question I notice a mention of dynamic columns at the end.
Please note that the above query (or any other pure-sql solution, PIVOT and CROSS APPLY included) only works for a fixed set of columns. This is because a pure SQL query can only returned a pre-defined, fixed set of columns. If you want a dynamic solution, then you need dynamic SQL (that is: prepare a query string, then execute it).
On the other hand, the above statement can easily be extended to handle more values from the additional table, by adding max(case when ... then ... end) expressions.
Related
I have various SQL queries, which return me unique / distinct value from DB, (or count them),
like:
SELECT buyer as counterparty
FROM public.order
UNION
SELECT seller as counterparty
FROM public.order
or
SELECT COUNT(*)
FROM (
SELECT DISTINCT p
FROM public.order
CROSS JOIN LATERAL (VALUES(seller),(buyer)) AS C(p)
) AS internalQuery
Example structure of my table:
id buyer seller
0 A B
1 B A
2 B D
3 D A
4 A D
Desired result:
3 or A,B,D
I'd like to rewrite them with TypORM query builder, but I can't figure out, how to replace CROSS JOIN LATERAL (VALUES(seller),(buyer)) AS C(p) or UNION in my case. TypeORM is pretty poor with examples and doc coverage in this case.
Does there any option with that?
I have seen various methods like .getCount and .distinct(true) which could help me and easily find the solution for one column.
So I understood, that if I want to find the exact number, instead of doc results, I should use .getCount instead of .getMany
But I can't understand, how to select (and unite) values from multiple columns via typeORM to receive distinct values from multiple columns.
I am working with PostgrSQL, so when I am trying:
const query = repository.createQueryBuilder('order')
.distinctOn(['buyer', 'seller'])
.limit(100)
.getMany()
I receive docs with each distinct value in each field, so instead of 3 I get 6 values (3 distinct by column1, and 3 by column2)
Am Having the Tables in SQL server as Super and Sub types like below. Now if i have to get list of Furnitures then how can i get the list?
Furniture table:
Id FurnituretypeId NoofLegs
-------------------------------
1 1 4
2 2 4
FurnitureType table:
Id Name
-----------------
1 chair
2 cot
3 table
Chair Table:
Id Name CansSwing CanDetachable FurnitureId
------------------------------------------------------------
1 Chair1 Y Y 1
Cot Table:
Id Name CotType Storage StorageType FurnitureId
-------------------------------------------------------------------
1 Cot1 Auto Y Drawer 2
How can i get the entire furniture list as some of them are chair and some of them are cot. How can i join the these tables with furniture table and get the list?
Hmmm . . . union all and join?
select cc.*, f.*
from ((select Id, Name, CansSwing, CanDetachable,
NULL as CotType, NULL as Storage, NULL as StorageType, FurnitureId
from chairs
) union all
(select Id, Name, NULL as CansSwing, NULL as CanDetachable,
CotType, Storage, StorageType, FurnitureId
from cots
)
) cc join
furniture f
on cc.furnitureid = f.id;
This is a classical learning problem, that's why I'm not giving you the code to solve this but all the insights you need to do so.
You have multiple approaches possible, but I'm describing two simple ones:
1) Use the UNION statement to join two separate queries one for Chair and the other for Cot, bare in mind that both SELECT have to return the same structure.
SELECT
a1,
a2,
etc..
FROM table1 a1
JOIN table2 a2 ON a1.some = a2.some
UNION
SELECT
a1,
a3,
etc..
FROM table1 a1
JOIN table3 a3 ON a1.some = a3.some
2) You can do it all in one SELECT statement using a LEFT JOIN to both tables and and in the select using COALESCE or ISNULL to get the values for one table or the other. In the WHERE condition you have to force one or the other join to be not null.
SELECT
a1,
COALESCE(a2,a3) as col2
FROM table1
LEFT JOIN table2 a2 ON a1.some = a2.some
LEFT JOIN table3 a3 ON a1.some = a3.some
WHERE
a2.some IS NOT NULL
OR a3.some IS NOT NULL
Mapping objects into relational models takes a degree of understanding of what is possible vs. what is wise in an RDBMS. Object oriented database systems tried to go after problems like this (generally without much success) precisely because the problem statement is arguably not the right one.
Please consider just putting all of these in one table. Then use null for the fields that don't really matter for each sub-type. You will likely end up being a lot happier in the end since you can spend less time at runtime doing joins and instead just query the information you need and use indexing on the same table to find the fasted path for each query you want to run.
SELECT * FROM CombinedTable;
I have two tables, one with orders and another with order comments. I want to join these two tables. They are joined on a column "EID" which exists in both tables. I want all orders. I also want to see all comments with only certain criteria AND all other comments should be set to null. How do I go about this?
Orders Table
Order_Number
1
2
3
4
Comments Table
Comments
Cancelled On
Ordered On
Cancelled On
Cancelled On
In this example I would like to see for my results:
Order_Number | Comments
1 | Cancelled On
2 | Null
3 | Cancelled On
4 | Cancelled On
Thanks!
This seems like a rather trivial left join.
select o.order_number, c.comments
from orders o
left join comments c
on o.eid = c.eid
and (here goes your criteria for comments)
Tested on Oracle, there might be subtle syntax differences for other DB engines.
It depends on one condition:
Are you trying to SET the other comments to null? (replace the values in the table)
or
Are you trying to DISPLAY the other comments as null? (dont display them)
If you want to change the values in the table use
UPDATE `table` SET `column` = null WHERE condition;
otherwise use:
SELECT column FROM table JOIN othertable WHERE condition;
Sorry if this is a basic question. I'm fairly new to SQL, so I guess I'm just missing the name of the concept to search for.
Quick overview.
First table (items):
ID | name
-------------
1 | abc
2 | def
3 | ghi
4 | jkl
Second table (pairs):
ID | FirstMember | SecondMember Virtual column (pair name)
-------------------------------------
1 | 2 | 3 defghi
2 | 1 | 4 abcjkl
I'm trying to build the virtual column shown in the second table
It could be built at the time any entry is made in the second table, but if done that way, the data in that column would get wrong any time one of the items in the first table is renamed.
I also understand that I can build that column any time I need it (in either plain requests or stored procedures), but that would lead to code duplication, since the second table can be involved in multiple different requests.
So is there a way to define a "virtual" column, that could be accessed as a normal column, but whose content is built dynamically?
Thanks.
Edit: this is on MsSql 2008, but an engine-agnostic solution would be preferred.
Edit: the example above was oversimplified in multiple ways - the major one being that the virtual column content isn't a straight concatenation of both names, but something more complex, depending on the content of columns I didn't described. Still, you've provided multiple paths that seems promising - I'll be back. Thanks.
You need to join the items table twice:
select p.id,
p.firstMember,
p.secondMember,
i1.name||i2.name as pair_name
from pairs as p
join items as i1 on p.FirstMember = i1.id
join items as i2 on p.SecondMember = i2.id;
Then put this into a view and you have your "virtual column". You would simply query the view instead of the actual pairs table wherever you need the pair_name column.
Note that the above uses inner joins, if your "FirstMember" and "SecondMember" columns might be null, you probably want to use an outer join instead.
You can use a view, which creates a table-like object from a query result, such as the one with a_horse_with_no_name provided.
CREATE VIEW pair_names AS
SELECT p.id,
p.firstMember,
p.secondMember,
CONCAT(i1.name, i2.name) AS pair_name
FROM pairs AS p
JOIN items AS i1 ON p.FirstMember = i1.id
JOIN items AS i2 ON p.SecondMember = i2.id;
Then to query the results just do:
SELECT id, pair_name FROM pair_names;
You could create a view for your 'virtual column', if you wanted to, like so:
CREATE VIEW aView AS
SELECT
p.ID,
p.FirstMember,
p.SecondMember,
a.name + b.name as 'PairName'
FROM
pairs p
LEFT JOIN
items a
ON
p.FirstMember = a.ID
LEFT JOIN
items b
ON
p.SecondMember = b.ID
Edit:
Or, of course, you could just use a similar select statement every time.
When selecting from tables you can name the results of a column using AS.
SELECT st.ID, st.FirstMember, st.SecondMember, ft1.Name + ft2.Name AS PairName
FROM Second_Table st
JOIN First_Table ft1 ON st.FirstMember = ft1.ID
JOIN First_Table ft2 ON st.SecondMember = ft2.ID
Should give you something like what you are after.
I have a single table of activities, some labelled 'Assessment' (type_id of 50) and some 'Counselling' (type_id of 9) with dates of the activities. I need to compare these dates to find how long people wait for counselling after assessment. The table contains rows for many people, and that is the primary key of 'id'. My problem is how to produce a result row with both the assessment details and the counselling details for the same person, so that I can compare the dates. I've tried joining the table to itself, and tried nested subqueries, I just can't fathom it. I'm using Access 2010 btw.
Please forgive my stupidity, but here's an example of joining the table to itself that doesn't work, producing nothing (not surprising):
Table looks like:
ID TYPE_ID ACTIVITY_DATE_TIME
----------------------------------
1 9 20130411
1 v 50 v 20130511
2 9 20130511
3 9 20130511
In the above the last two rows have only had assessment so I want to ignore them, and just work on the situation where there's both assessment and counselling 'type-id'
SELECT
civicrm_activity.id, civicrm_activity.type_id,
civicrm_activity.activity_date_time,
civicrm_activity_1.type_id,
civicrm_activity_1.activity_date_time
FROM
civicrm_activity INNER JOIN civicrm_activity AS civicrm_activity_1
ON civicrm_activity.id = civicrm_activity_1.id
WHERE
civicrm_activity.type_id=9
AND civicrm_activity_1.type_id=50;
I'm actually wondering whether this is in fact not possible to do with SQL? I hope it is possible? Thank you for your patience!
Sounds to me like you only want to get the ID numbers where you have a TYPE_ID entry of both 9 and 50.
SELECT DISTINCT id FROM civicrm_activity WHERE type_id = '9' AND id IN (SELECT id FROM civicrm_activity WHERE type_id = '50');
This will give you a list of id's that has entries with both type_id 9 and 50. With that list you can now go and get the specifics.
Use this SQL for the time of type_id 9
SELECT activity_date_time FROM civicrm_activity WHERE id = 'id_from_last_sql' AND type_id = '9'
Use this SQL for the time of type_id 50
SELECT activity_date_time FROM civicrm_activity WHERE id = 'id_from_last_sql' AND type_id = '50'
Your query looks OK to me, too. The one problem might be that you use only one table alias. I don't know, but perhaps Access treats the table name "specially" such that, in effect, the WHERE clause says
WHERE
civicrm_activity.type_id=9
AND civicrm_activity.type_id=50;
That would certainly explain zero rows returned!
To fix that, use an alias for each table. I suggest shorter ones,
SELECT A.id, A.type_id, A.activity_date_time,
B.type_id, B.activity_date_time
FROM civicrm_activity as A
JOIN civicrm_activity as B
ON A.id = B.id
WHERE A.type_id=9
AND B.type_id=50;