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)
Related
How do I create a query that returns only records in one table that have no foreign key relations with a particular attribute? I'm not even sure how to properly formulate the question, so I'm giving an example below:
I have Table B. It has an ID and other stuff that's not important.
I have Table C. It has an ID, an attribute (call it Available) which is only ever 'Yes' or 'No'.
Each record in Table B may have zero or more records in Table C related to it. They are connected by Table BC_Line, where each record has a FK for B_ID and a FK for C_ID. Hence, if records C_ID=1 and C_ID=2 are related to B_ID=1, then BC_Line has two records: (B_ID_FK=1 C_ID_FK=1) and (B_ID_FK=1 C_ID_FK=2).
I want a query that returns ONLY records in B that have NO associated records in C with C_Available='No'. A record in B might have several related records in C, all with 'Yes', and that would be shown. A record in B might have several related records in C all with 'No', that would NOT be shown. A record in B might also have records in C, some 'Yes' and some 'No', but that record would still not be shown. All related C records must be 'Yes'.
I'm not sure how to do it. I understand how to create queries and how to do Joins, but I do not know how to combine them in such a way as to get what I want. It's possible this is a well known problem, but I haven't been able to find the answer, partly because I have difficulty articulating my problem.
For the record, I am using Oracle.
You could use EXISTS:
SELECT *
FROM TableB b
WHERE NOT EXISTS (SELECT 1
FROM TableC c
WHERE c.C_Available='No'
AND b.B_ID_FK =c.C_ID);
Note! I've assumed that c.C_Available is defined as NOT NULL and it could hold only Yes/No values.
You could also use the left join method.
select b.*
from tableB b left join bc_line on b.b_id = bc.b_id
left join tableC c on bc.c_id = c.c_id
and c.c_available = 'No'
where c.c_id is null
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.
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.
Lets suppose that I have a table A with couple of columns. I work with tables, where there is no index on the entries, since they are 'historical' tables. I use one specific column, though, to sort of identify my things. Lets call this ID.
If you'd make a query like the one below, sometimes you'd get one line back, other cases a few.
SELECT * FROM A WHERE ID = '<something>'
Lets say I have two more tables, B and C. Both have ID columns, like A.
Also, some of the IDs in A, are also in B OR C. IDs existing in B CANNOT exist in C. And ALL IDs in A EXIST in either B OR C.
B and C contain extra information, which I'd like to join to A at the same SELECT.
My problem is, that they would only provide extra information. I do not want extra lines in my output..
To make it more clear: my selection from A returns a hundred lines of output.
When I left/right/inner join B table, I —probably— will have less lines as output. Same thing with joining C.
AND FINALLY, my question is:
Is there a way to join table B only on those IDs, which exist in B and vice versa? (And it I would want it in the same SELECT.... statement.)
If you don't want extra lines in your output, you could do something like this:
select *
from A join
(select B.*
from B
group by B.id
) B
on A.id = B.id;
This would choose arbitrary values from B for each id and join them back to A. Is this what you want?
Well it seems like you should build some left join between A and two "Select MAX"s: one from table B, the other one from table C.
And if you do not want 'duplicate' IDs from table A, a 'group by' on table A should help.