There Is three table Master, Regular and Customer.
I'm saving ControlId in customer master for both Master and Regular. I want to get Profile from Master from the Customer Record.
By using below Query. I'm able to get MasterID from regular But I want Profile.
Query
select * from customer where refId='R000003'
(select ControlId from regular where LicenseId='R000003')
Result
Master Table
Regular Table
My Query Is..
SELECT Customer.CustomerId, Regular.LicenseId, Regular.ControlId,
Master.FullName, Master.profile
FROM Customer INNER JOIN
Regular ON Customer.RefId = Regular.LicenseId INNER JOIN
Master ON Regular.ControlId = Master.MasterId
WHERE (Customer.RefId = 'R000003')
But Its showing Regural's only I want Masters record also...
Is this what you mean? I'm not sure..
select regular.ControlId, master.profile
from regular r inner join master m ON (r.controlId = m.masterId)
where regular.LicenseId='R000003'
Posting an image of your data is not helpful. No one is going to type this in.
Paste the sample.
I am going to guess that RefId and LicenseId refer to each other. I think this is the query you want:
select c.*, m.profile
from customer c join
regular r
on c.refId = r.LicenseId join
master m
on r.controlId = m.MasterId;
I would advise you to fix your tables. Join keys in different tables should have similar names, so you know they line up. In fact, I almost always name my join keys as "Id", so this query would look more like like:
select c.*, m.profile
from customer c join
regular r
on c.CustomerId = r.CustomerId join
master m
on r.MasterId = m.MasterId;
Related
I am working on a query that has fields called ios_app_id, android_app_id and app_id.
The app_id from downloads table can be either ios_app_id or android_app_id in the products table.
Is it correct that because of that I cannot just run a simple join of downloads and products table on on p.ios_app_id = d.app_id and then join again on on p.android_app_id = d.app_id? Would that cause an incorrect number of records?
select p.product_id, d.date, d.downloads,
from products p
inner join download d
on p.ios_app_id = d.app_id
UNION
select p.product_id, d.date, d.downloads
from products p
inner join download d
on p.android_app_id = d.app_id
I would try:
select p.product_id, d.date, d.downloads,
from products p
inner join downloads d
on p.ios_app_id = d.app_id
inner join downloads d
on p.android_app_id = d.app_id
Basically I am trying to understand why the union here is needed instead of just joining the two fields twice? Thank you
Just join twice:
select p.product_id,
coalesce(di.date, da.date),
coalesce(di.downloads, da.downloads)
from products p left join
downloads di
on p.ios_app_id = di.app_id left join
downloads da
on p.android_app_id = da.app_id;
This should be more efficient than your method with union. Basically, it attempts joining using the two ids. The coalesce() combines the results into a single column.
Remember that the purpose of an INNER JOIN is to get the values that exists on BOTH sets of data (lets called them table A and table B), using a specific column to join them. In your example, if you try to do the INNER JOIN twice, what would happen is that the first time you execute the INNER JOIN, the complete PRODUCTS table is your table A, and you obtain all the products that have downloaded the ios_app, but now (and this is the key part) this result becomes your new dataset, so it becomes your new table A for the next inner join. And thats the issue, cause what you would want is to join the whole table again, not just the result of the first join, but thats not how it works. This is why you need to use the UNION, cause you need to obtain your results independently and then add them.
An alternative would be to use LEFT JOIN, but you could get null values and duplicates -and its not too "clean"-. So, for your particular case, I think using UNION is much clearer and easier to understand.
If you do left join in first query it will work.
create table all_products as (select p.product_id, d.date, d.downloads,
from products p
left join downloads d
on p.ios_app_id = d.app_id)
select a.product_id, d.date, d.downloads from all_products a left join downloads d
on a.android_app_id = d.app_id inner join
I have the following DB structure:
And right now I can't make up a query to get
a creator data, admin data and tech data from item_contacts...
What kind of JOIN I need to use and how?
I think you want 3 joins on item_contacts - one for each column whose data you want to recover:
select
i.*,
cc.data as creator_data,
ca.data as admin_data,
ct.data as tech_data
from items i
inner join item_contacts cc on cc.contact_id = i.creator_id
inner join item_contacts ca on ca.contact_id = i.admin_id
inner join item_contacts ct on ct.contact_id = i.tech_id
Here is my ERD for SQL Server:
https://c2.staticflickr.com/6/5832/23786188186_d6f1d93132_o.jpg
I need to find out which books are associated with each publisher.
USE BookStoreDB
SELECT ProductID
FROM Books
INNER JOIN [Publishers] PublisherID ON PublishersID = ProductID
I'm assuming I just didn't create the INNER JOIN command correctly?
SELECT p.PublisherID, b.ProductID
FROM Books b
INNER JOIN Publishers p ON p.PublisherID = b.PublisherID
The ON part of a join defines how the two tables are related to each other. In your case, it would be:
INNER JOIN Publishers ON (Books.PublisherID = Publishers.PublisherID)
If you put something between the name of the table, and the ON, it's treated as an alias. You can (and should) also use these aliases in your SELECT
FROM Books B
INNER JOIN Publishers P ON (B.PublisherID = P.PublisherID)
Finally, you probably want to select information that will actually tell you who the publisher is:
SELECT B.ISBN, P.CompanyName
FROM Books B
INNER JOIN Publishers P ON (B.PublisherID = P.PublisherID)
I have three tables:
COLLECTION
PERSON
PERSON_COLLECTION
where PERSON_COLLECTION is a mapping table id|person_id|collection_id
I now want to select all entries in collection and order them by person.name.
Do I have to join the separate tables with the mapping table first and then do a join again on the results?
SELECT
c.*,
p.Name
FROM
Collection c
JOIN Person_Collection pc ON pc.collection_id = c.id
JOIN Person p ON p.id = pc.person_id
ORDER BY p.Name
Not sure without the table schema but, my take is:
SELECT
c.*,
p.*
FROM
Person_Collection pc
LEFT JOIN Collection c
ON pc.collection_id = c.id
LEFT JOIN Person p
ON pc.person_id = p.id
ORDER BY p.name
The order you join won't break it but depending on which sql product you're using may effect performance.
You need to decide if you want ALL records from both/either table or only records which have a matching mapping entry, this will change the type of join you need to use.
I have 2 tables , one showing me customer addresses and one other table showing all the order data. i would like to query the two tables using a JOIN so that i can get a result set shwoing me all the email addresses for customers that have not ordered in the last year.
so far i have this , but my inner join is not working, if you may help:
SELECT SHH.CUST_NO,ADR.EMAIL
FROM SALES_HISTORY_HEADER SHH,ADDRESS ADR
INNER JOIN ADR ON
SHH.CUST_NO = ADR.CUST_NO
GROUP BY SHH.CUST_NO
HAVING Max(SHH.INVOICE_DATE) < '20100728'
You were mixing join styles. If you're going to use explicit joins (and you should) then you specify the second table on the JOIN rather than listing all the tables in the FROM clause.
SELECT SHH.CUST_NO,ADR.EMAIL
FROM SALES_HISTORY_HEADER SHH
INNER JOIN ADDRESS ADR
ON SHH.CUST_NO = ADR.CUST_NO
GROUP BY SHH.CUST_NO, ADR.EMAIL
HAVING Max(SHH.INVOICE_DATE) < '20100728'