In this question it's finally clicked how to write joins between multiple tables, where they link in a line e.g.
Table A - Table B - Table C
Where Table A references Table B, and Table B references Table C and so on.
What I still don't understand is how to reference the situation where Table A references Table B as above and also reference Table D.
In implicit Joins I can get the following to work, but want to move it to explicits...
SELECT a.name, b.office, c.firm, d.status
FROM job a, depts b, firms c, statuses d
WHERE a.office = b.ref
AND b.firm = c.ref
AND a.status = d.ref
Any tips?
SELECT
a.name,
b.office,
c.firm,
d.status
FROM
job a
JOIN depts b ON a.office = b.ref
JOIN firms c ON b.firm = c.ref
JOIN statuses d ON a.status = d.ref
That's as detailed as I could get on such an obscure question. You didn't describe what exactly does "link" mean in your case. So I don't know, maybe you need left join.
Related
I have a PostgreSQL query like below and I want to join a new table to that when rateid>100
CASE WHEN rateid<100 Then
Select * FROM rate as A, plan AS B, room AS C
WHERE A.id=B.rateid
AND B.roomid=C.id
ELSE
Select * FROM rate as A, plan AS B, room AS C, hotel AS D
WHERE A.id=B.rateid
AND B.roomid=C.id
AND C.hotelid=D.id
END
Can I know is there any way to join hotel table when rateid>100?
In your question you say "when rateid>100", I assume you mean "rateid>=100" because in the code you use "rateid<100"
I also changed the old-style to new-style joins.
The on-clause tells SQL what to join, so adding "rateid>=100" should solve the problem (When I understand your question correctly)
select
*
from
rate as A,
inner join plan as B on
A.id = B.rateid
inner join room as C on
B.roomid = C.id
and rateid >= 100
I haven't done a SQL statement in about 10 years. A little help?
Table A:
ID, Title
1,"hello"
2,"world"
Table B:
ID, OBJ_ID
1,23
2,24
Table C:
ID, Name
23,"foo"
23,"bar"
24,"hi"
24,"pangea"
A.ID = B.ID
B.OBJ_ID = C.ID
One (A) to One (B) to Many (C)
Result needed:
A.Title, C.Name(s)
hello,foo,bar
world,hi,pangea
Thanks.
I know I'm flat out asking for answer, but which JOIN would I use? Thanks.
MariaDB, I'm trying to extract some data from someone's WP site. Why table B is there, is beyond me.
Thanks #jarlh
select a.title, c.name
from c
join b on b.obj_id = c.id
join a on a.id = b.obj_id
SELECT A.Title, C.Name
FROM A join B on A.ID=B.ID JOIN C ON B.ID=C.ID
ORDER BY A.Title, C.Name
If you want to have one row per title with all values from table C, consider using pivot.
I have table B with bcust(4-digit integer) and bdate(date) columns. I also have table C with ccust(4-digit integer) and cdate(date). I want to show the records from table c where cdate occurred after bdate.
I guess, maybe you're looking for this?
SELECT c.*
FROM c
INNER JOIN b
ON b.bcust = c.ccust
AND b.bdate < c.cdate;
I assumed, that the records are linked via the bcust and ccust columns.
Although you did not mention anything on how the records in both tables are related, I guess that records are related if bcust = ccust.
Then something like this should do what you want:
SELECT c.*
FROM tableC c
INNER JOIN tableB b ON c.ccust = b.bcust
WHERE c.cdate > b.bdate
So I've been given a task where i should present the following:
ID, LNAME, FNAME, MNAME, BIRTH_DATE, RELG_CODE, NAT_CODE, PT_STATUS, RM_NO, DTTM_ADM
The tables are:
HISR_CODES, PASR_NAMES, PASR_PROFILE, PAST_PATIENT_ADM
--Viewing them using DESC--
So while I viewed them, I was told that the ID on these tables are the same. So what I did so far in the coding (I'll finish the rest but I need to make sure this works first):
SELECT
A.ID,
A.LNAME,
A.FNAME,
A.MNAME,
A.BIRTH_DATE,
C.RELG_CODE,
C.NAT_CODE,
B.PT_STATUS,
B.RM_NO,
B.DTTM_ADM
FROM
PASR_NAMES A,
PASR_PROFILE B,
PAST_PATIENT_ADM C,
HISR_CODES D
WHERE
A.ID = B.ID
AND
B.ID = C.ID
AND
C.ID = D.ID
Is there a way to tell that all of the ID's from the tables are the same? A simpler code than going on like this:
WHERE
A.ID = B.ID
AND
B.ID = C.ID
AND
C.ID = D.ID
Or is JOIN - ON the only option for this?
You can use NATURAL JOIN as below:
SELECT
A.ID,
A.LNAME,
A.FNAME,
A.MNAME,
A.BIRTH_DATE,
C.RELG_CODE,
C.NAT_CODE,
B.PT_STATUS,
B.RM_NO,
B.DTTM_ADM
FROM
PASR_NAMES A
NATURAL JOIN PASR_PROFILE B
NATURAL JOIN PAST_PATIENT_ADM C
NATURAL JOIN HISR_CODES D;
From Oracle Reference, "A natural join is based on all columns in the two tables that have the same name." So, there is a chance that the joins happen based on other columns as well. Therefore, it is recommended that you still use the INNER JOIN syntax and explicitly specify the JOIN columns.
References:
NATURAL JOIN on Oracle® Database SQL Language Reference
Related SO question
Use the proper join syntax:
FROM PASR_NAMES A JOIN
PASR_PROFILE B
ON A.ID = B.ID JOIN
PAST_PATIENT_ADM C
ON B.ID = C.ID JOIn
HISR_CODES D
ON C.ID = D.ID
Or:
FROM PASR_NAMES A JOIN
PASR_PROFILE B
USING (ID) JOIN
PAST_PATIENT_ADM C
USING (ID)
HISR_CODES D
USING (ID)
I would discourage you from using the natural join. It might seem like the right thing at first. However, the semantics of the query are highly dependent on the structure of the tables. If columns are renamed, removed, or added, the query might still work but produce highly unexpected results.
I have 3 tables A, B, C. There is a relationship between tables A and C while there is a relationship between tables B and C . There is no relationship between A and B.
What I would really like to do is get a list of all the records from B when there are records in C related to B given a value from A .
Please let me know, if this is not clear enough
Thanks
you can right query something like this...
SELECT B.* FROM B
INNER JOIN C ON C.aa = B.aa
INNER JOIN A ON A.bb = C.bb
WHERE A.cc = #yourvalue
#yourvalue is your value on which bases you need to select the value from B table. if you need match mutliple values from A then you need to change bit of query some thing like this...
WHERE A.cc IN (#val1,#val2,#val3....,#valNth)
In this query we have used INNER JOIN so it will gives only those records which are common on both the tables LIKE if you only join B with C then it will give the records which are common in B and C and then you join A with C then it will give those records which are common in A and C.
So suppose in B there is records something like 1,2,3 and in C there is 2,3,4,5 and in A there is 1,3,4,5
so the output of above query (without applying WHERE cause) is 1,3 only because this is common in all three table A,B,C.
you can got more information for joins in sqlserver by refering this links..
http://blog.sqlauthority.com/2009/04/13/sql-server-introduction-to-joins-basic-of-joins/
http://www.dotnet-tricks.com/Tutorial/sqlserver/W1aI140312-Different-Types-of-SQL-Joins.html
http://www.aspdotnet-suresh.com/2011/12/different-types-of-joins-in-sql-server.html
Simple math dictates if there is a relationship between A and C, and a relationship between B and C, there is, albeit by association, a relationship between A and B (through C).
Thus you will need to join all three together, going from A, through C, to B:
SELECT B.*
FROM A
JOIN C ON A.x = C.x
JOIN B ON B.y = C.y
WHERE A.z = #z