I know there are similar questions, but I can't find solution to what I need to do.
First of all I have 2 tables :
SD.Airlines (16k+ rows)
SD.AirlineRatings (405 rows)
I need to find which records form SD.AirlineRatings do I have in SD.Airlines, I did this :
SELECT b.Name AS Airline FROM SD.Airlines b
LEFT JOIN SD.AirlineRatings a ON a.AirlineName = b.Name
WHERE a.AirlineName IS NOT NULL;
Works fine, showed me 249/405 records. Now... If I need to compare those 249 records towards SD.AirlineRatings and check which ones I don't have.
I bet answer is simple but I don't know SQL that much.
Thanks
If you want records in AirLines ratings that are also in Airlines, then I would recommend EXISTS or IN:
select a.*
from sd.Airlines a
where exists (select 1 from sd.AirlineRatings ar where ar.AirlineName = a.Name);
If you want unrated airlines:
select a.*
from sd.Airlines a
where not exists (select 1 from sd.AirlineRatings ar where ar.AirlineName = a.Name);
And, if you want ratings on airlines that don't exist, you would swap the two tables in the query.
Related
Im trying to SELECT all rows from one table with a specific condition. Im using Oracle PLSQL.
I have two tables:
Books
id
name
Page
id
words
book_id
One book can have multiple pages.
I want to find all books that don't have any page with 50 words.
The only solution I've found is to make a Left Outer Join and then filter by nulls.
Select * from Books b
LEFT OUTER JOIN Page p on b.id = p.book_id and p.words = 50
where p.words is null
I think its not a good solution, but it works, do you know any other way to do that?
I don't want to take any information about Pages. If I make a normal join and then I apply the condition I get N rows for a Book, and I only want to get 1 row for each Book
Thanks.
You could adjust your select so it is only b.*.
Possibly a more common alternative is not exists:
select b.*
from Books b
where not exists (select 1
from Page p
where b.id = p.book_id and p.words = 50
);
The two methods should have similar performance characteristics.
I have two tables. Table 1 has about 750,000 rows and table 2 has 4 million rows. Table two has an extra ID field in which I am interested, so I want to write a query that will check if the 750,000 table 1 records exist in table 2. For all those rows in table 1 that exist in table 2, I want the respective ID based on same SSN. I tried the following query:
SELECT distinct b.UID, a.*
FROM [Analysis].[dbo].[Table1] A, [Proteus_8_2].dbo.Table2 B
where a.ssn = b.ssn
Instead of getting 750,000 rows in the output, I am getting 5.4 million records. Where am i going wrong?
Please help?
You're requesting all the rows in your select if b.UID is a unique field in column two.
Also if SSN is not unique in table one you can get the higher row count than the total row count for table 2.
You need to consider what you want from table 2 again.
EDIT
You can try this to return distinct combinations of ssn and uid when ssn is found in table 2 provided that ssn and uid have a cardinality of 1:1, i.e., every unique ssn has a single unique uid.
select distinct
a.ssn,b.[UID]
from [Analysis].[dbo].[Table1] a
cross apply
( select top 1 [uid] from [Proteus_8_2].[dbo].[Table2] where ssn = a.ssn ) b
where b.[UID] is not null
Try with LEFT JOIN
SELECT distinct b.UID, a.*
FROM [Analysis].[dbo].[Table1] A LEFT JOIN [Proteus_8_2].dbo.Table2 B
on a.ssn = b.ssn
Since the order detail table is in a one-many relationship to the order table, that is the expected result of any join. If you want something different, you need to define for us the business rule that will tell us how to select only one record from the Order detail table. You cannot effectively write SQL code without understanding the business rules that of what you are trying to achieve. You should never just willy nilly select one record out of the many, you need to understand which one you want.
Wondering if anyone can point me in the right direction please.
I Have 3 tables...
Table A -
Code, Cost1, Cost2, Cost3
Table B -
Code, ID
Table C -
ID, Price
Basically I need to update the Price Field on Table C with (Cost1+Cost2+Cost3)
from Table A.
There is no direct link between the 2 tables, but A is linked to B via Code and B is linked to C via ID.
I can write a query to display Price and the Total Cost but can't get my head around how to do the Update.
Any pointers would be extremely welcome
Thanks
Andrew
UPDATE TC
SET Price=(TA.Cost1+TA.Cost2+TA.Cost3)
FROM TableA TA
INNER JOIN TableB TB ON TA.Code=TB.Code
INNER JOIN TableC TC ON TC.ID=TB.ID
I prefer writing my more complicated joins out first and then simply updating the alias. As you can see in the example, you could comment out the top two lines and simply put in a SELECT TC.ID,TA.Cost1+TA.Cost2+TA.Cost3 and see exactly what would change.
I really need to know the query to display another field which is I want to name it as "number_difference" between 2 tables that required a numeric (in this case as a quantity).
I have 2 tables that totally same, let say, I modify the value from table A so some value in table A different with table B. And I want to join it into 1 table that display rows that some values were modified. I already get the result by this query :
**
select a.T1, a.T2 a.T3 ... from A where not exists (select * from B
where a.T1=b.T1 and a.T2=b.T2 and a.T3=b.T3)
**
This query works well. But, I want to add more field, the difference number between this 2 field (quantity) in 2 different tables. So let say, a.T3 and b.T3 are quantities. And want to display it as "number_difference" next to field (T2) which I display. Sorry I can't post images, they say I need at least 10 reputation to post. Please help me master, how can I make it everytime I use join/inner join it always display soo many rows that I only need the rows which a value from 1 table I have modified.
Thanks in advance.
You can get something like this
Select * From A Where A.id not in( Select Id from B)
or
Select A.* From A left join B on A.id = B.id Where A.id <> B.id
If you are specifically targeting a situation with two identical tables, where one underwent UPDATE operations only (no INSERT), and you want to identify those records which were modified, then:
select a.* from a, b where a.id=b.id and ( a.c1!=b.c1 or a.c2!=b.c2)
I'm relatively new to sql so this may probably come off as a simple questions.
I have 3 tables A,B,C
B has a FK to A, and C has a FK to B
I would like to get all the distinct entries in A that has an entry in B that corresponds to an entry in C. With JOINs I currently have:
SELECT DISTINCT *
FROM Peoples p
INNER JOIN Contracts c
ON p.pkey=c.person_pkey
JOIN audits a ON c.contract_pkey=a.contract_issued_for;
So this returns the list of all people (with duplicates) with an audit. How do I get it so that instead of return columns of all the tables put together, but rather just all the columns that belong to table peoples and are unique entries?
Thanks in advance!
Replace
SELECT DISTINCT *
with
SELECT DISTINCT p.*
SELECT DISTINCT p.*
FROM Peoples p
...
The minimal change to your query would be to change * to p.*. However, I think a better approach is to use IN clauses rather than JOINs:
SELECT *
FROM Peoples
WHERE pkey IN
( SELECT person_pkey
FROM Contracts
WHERE contract_pkey IN
( SELECT contract_issued_for
FROM audits
)
)
;
This makes clear what the query is really doing: it's finding people who have contracts that audits have been issued for, and is not otherwise interested in those contracts or audits.