now i have 3 tables, for example A,B,C
the relation between them is A onetomany B, B onetomany C.
C is a table saved photos
now i want get data from A, but only the last photo each A.
the colomns maybe like this:
table a:
id a_msg
a1 msg in a
a2 msg in a
a3 msg in a
table b:
id b_msg a_id
b1 some data in b a1
b2 some data in b a1
b3 some data in b a2
b4 some data in b a3
table c:
id url createdate c_msg b_id
c1 /file/1.jpg 2014-12-01 06:55:54.600 some data in c b1
c2 /file/2.jpg 2014-12-01 06:55:54.601 some data in c b1
c3 /file/3.jpg 2014-12-01 06:55:54.602 some data in c b1
c4 /file/4.jpg 2014-12-01 06:55:54.603 some data in c b2
c5 /file/5.jpg 2014-12-01 06:55:54.604 some data in c b2
c6 /file/6.jpg 2014-12-01 06:55:54.605 some data in c b3
the result i want get
c_id url createdate c_msg b_msg b_id a_msg a_id
c6 /file/6.jpg 2014-12-01 06:55:54.605 some data in c some data in b b3 msg in a a1
c5 /file/5.jpg 2014-12-01 06:55:54.604 some data in c some data in b b2 msg in a a1
Sorry ,i don't know how to use tool to describle the table,hope you can easily understand what i mean.
if my description is not clear enough,i will edit the question,thank you if anyone can help me
Consider the following as an example :
create table table_a (id int,a_msg text);
create table table_b (id int,b_msg text,a_id int);
create table table_c (id int,url text,createdate timestamp with time zone,c_msg text ,b_id int);
and the data
insert into table_a values (1,'msg in table_a')
,(2,'2nd msg in table_a')
,(3,'3rd msg in table_a');
insert into table_b values (20,'msg in table_b',1)
,(21,'2nd msg in table_b',2)
,(22,'3rd msg in table_b',3);
insert into table_c values (30,'url','2014-12-01 06:55:54.600','msg in table_c',20)
,(31,'url 1','2014-12-01 06:55:54.604','2nd msg in table_c',21)
,(32,'url 2','2014-12-01 06:55:54.605','3rd msg in table_c',22);
to get the result you need to use INNER JOIN and to get the last two data use order by createdate desc limit 2
select c.id,c.url
,c.createdate
,c.c_msg,b.b_msg
,b.id bi_id,a.a_msg
,a.id a_id
from
table_c c inner join table_b b on c.b_id=b.id /* to get data from table_b */
inner join table_a a on b.a_id=a.id /* to get data from table_a */
order by createdate desc limit 2 /* DESC will sort from the highest date time values and LIMIT 2 will return two rows */
>SQLFIDDLE DEMO WITH OP'S DATA
Related
I am facing a problem which I do not know how to categorize. So, pardon me for the generic title. I have a dataset like:
Table1: Column1, Column2, Column3.
According to my business logic, for a pair of 'Column1 Column2', the Column3 can have only one unique value. So below table is a problematic one because of the second entry:
Table1
Column1 Column2 Column3
A1 B1 R
A1 B1 O << ERROR! for A1-B1 pair only one value on column3 is accepted
A2 B2 R
A2 B3 J
A3 B3 K
A4 B5 K
From above table I would like to find the problematic entries:
A1 B1 R
A1 B1 O
Thanks in advance for your help !
Using your example column names, you can run the following query to just see the Column1/Column2 pairs that have more than 1 value in Column 3.
SELECT Column1, Column2, COUNT(DISTINCT Column3) as Column3
FROM Table1
GROUP BY Column1, Column2
HAVING COUNT(DISTINCT Column3) > 1
You can omit the HAVING line to see the complete list of Column1/Column2 pairs.
In postgresql I got 4 tables
Table A:
-----------
a_id
a_date
Table B
-----------
a_id b_id
Table C:
-------------------
c_id
b_id
invoice_number
Table D
-------------------
d_id
invoice_number
value_D
Multiple records have value_D
I would like to select Table A, Table B, Table C and Table D, where a_date BETWEEN X AND Y.
However, I would also like to select all the other value_D that are not included in my selection (so A innerjoin B innerjoin C full outerjoin D)
my code
SELECT
Table A, Table B, Table C, Table D
FROM
Table A
JOIN
Table B ON A.a_id = B.a_id
JOIN
Table C ON B.b_id = C.b_id
FULL OUTER JOIN
Table D ON C.invoice_number = D.invoice_number
WHERE
A.a_date BETWEEN X AND Y;
It only shows D.value_d for the A.a_id, where A.a_date BETWEEN X and Y.
I would like however that D.value_d would also be shown for A.a_id, where A.a_date is also other.
I am kinda a newbie, so hopefully it is understandable and you could help me.
Thanks in advance
You can also add more conditions to the Where clause, for example:
"a_date BETWEEN X AND Y OR a_date > '2015-04-21'". This will retrieve the union of both conditions.
Regards
I think I solved it.
SELECT Table A, Table B, Table C, Table D
FROM Table A
JOIN Table B ON A.a_id = B.a_id
JOIN Table C ON B.b_id = C.b_id
JOIN Table D ON C.invoice_number = D.invoice_number
WHERE A.a_date BETWEEN X AND Y OR
D.value_D IN (SELECT D.value_D
FROM Table D
JOIN Table C ON D.invoice_number on C.invoice_number
JOIN Table B ON C.b_id = B.b_id
JOIN Table A ON B.a_id = A.a_id
WHERE A.a_date BETWEEN X AND Y);
Thank you all for the help guys!
Table a:
id value0
101 a1
102 a2
103 a3
Table b:
id value1
101 b1
101 b2
101 b3
Table c:
id value2
101 c1
103 c3
103 c4
Rezult table:
id value0 value1 value2
101 a1 b1 0
101 a1 b2 0
101 a1 b3 0
101 a1 0 c1
102 a2 0 0
103 a3 0 c3
103 a3 0 c4
Is it possible to produce rezult table from tables a, b, c with one query (without creating two tables and join them)? Maybe there is a possibility to do it by using only left joins?
This may help you-
select t1.id, t2.id, t3.id
from tablea t1 inner join tableb t2 on t1.id = t2.id
inner join tablec t3 on t2.id=t3.id
group by id
If you have a base table, select that and do a left join to the others. If none of your tables can act as a base table, you can use full joins (both works as outer joins):
select *
from table_a
full join table_b using (id)
full join table_c using (id)
This will select sql NULLs, where there is no data, but you can use COLAESCE(value0, 'N/A'), etc. to select some default data.
I have a Table which has 2 fields say A,B. Suppose A has values a1,a2.
Corresponding records for a1 in B are 1,2,3,x,y,z.
Corresponding records for a2 in B are 1,2,3,4,d,e,f
I need a a query to be written in DB2, so that it will fetch the common records in B for each record in A (a1 and a2).
So here the output would be :
A B
a1 1
a1 2
a1 3
a2 1
a2 2
a2 3
Can someone please help on this?
Try something like:
SELECT A, B
FROM Table t1
WHERE (SELECT COUNT(*) FROM Table t2 WHERE t2.B = t1.B)
= (SELECT COUNT(DISTINCT t3.A) FROM Table t3)
ORDER BY A, B
This might not be 100% accurate as I can't test it out in DB2 so you might have to tweak the query a little bit to make it work.
with t(num) as (select count(distinct A) from table)
select t1.A, t1.B
from table t1, table t2, t
where t1.B = t2.B
group by t1.A, t1.B, num
having count(*) = num
Basically, the idea is to join the same table with column B and filter out just the ones that match exactly the same number of times as the number of elements in column A, which indicates that it is a common record out of all the A values.
I have two master tables CompanyMaster, ActivityMaster for a child table CompanyActivities
ActivityMaster
ACTIVITYID ACTIVITYNAME
A1 testActivity
A2 someActivity
A3 otheractivity
A4 someotheractivity
A5 anyotheractivity
CompanyMaster
COMPANYID COMPANYNAME
C1 testcompany
C2 ACompany
C3 MyCompany
C4 SomeCompany
C5 ZCompany
C6 Company123
C7 ComapnyABC
CompanyActivities - The COMPANYID in CompanyActivities is having a primarykey-foreighkey relation ship with COMPANYID in CompanyMaster (primary key table) and ACTIVITYID is having a primarykey-foreighkey relation ship with ACTIVITYID in ActivityMaster(primary key table)
COMPANYID ACTIVITYID
C1 A1
C1 A3
C3 A1
C3 A2
C4 A5
C5 A1
C6 A3
C7 A3
I want to do write a query to get the following output where all the rows in ACTIVITYID column of the ActivityMaster table will be converted to columns
Output
Companies A1 A2 A3 A4 A5
C1 Y N Y N N
C2 N N N N N
C3 Y Y N N N
C4 N N N N Y
C5 Y N N N N
C6 N N Y N N
C7 N N Y N N
The output table displays all the companies as rows in the first column and all the activities are shown as columns that start after the first column, if there is row that contains both ACTIVITYID and COMPANYID it will set to Y in output otherwise it would be set to N
eg- COMPANYID C1 is having an activity ACTIVITYID A1 in CompanyActivities table so the first row in the second column that comes just below A1 and in the right to C1 is set Y, whereas C1 and A2 are not having a row, so the third column in the first row is set to N
I am using C#.net and 4 for loops to achieve the output now which is talking a heavy toll on the performance of the application, So i would like to do this using a query, I have searched for pivot queries, but all the examples i found knows the column names before-hand, which i don't i only get the names of the column names by querying the ActivityMaster.
create table #CompanyMaster (COMPANYID int, COMPANYNAME varchar(30))
create table #ActivityMaster (ACTIVITYID int, ACTIVITYNAME varchar(30))
create table #CompanyActivities (COMPANYID int, ACTIVITYID int)
insert into #CompanyMaster
SELECT 1, 'Company A'
union all
SELECT 2, 'Company B'
insert into #ActivityMaster
SELECT 101, 'Activity X'
union all
SELECT 102, 'Activity Y'
union all
SELECT 103, 'Activity Z'
insert into #CompanyActivities
select 1, 102
union all
select 2, 101
-- build activities column names
--case [Activity X] when 0 then ''N'' else ''Y'' end as [Activity X],
--case [Activity Y] when 0 then ''N'' else ''Y'' end as [Activity Y],
--case [Activity Z] when 0 then ''N'' else ''Y'' end as [Activity Z]
declare #activities nvarchar(max)
set #activities
= (
select 'case [' + ACTIVITYNAME + '] when 0 then ''N'' else ''Y'' end as [' + ACTIVITYNAME + '],' + char(10)
from #ActivityMaster
for xml path('')
)
set #activities = substring(#activities, 0, len(#activities)-1)
declare #activities_for nvarchar(max)
-- build activities column names in for
--[Activity X], [Activity Y], [Activity Z]
set #activities_for
= (
select '[' + ACTIVITYNAME + '],' + char(10)
from #ActivityMaster
for xml path('')
)
set #activities_for = substring(#activities_for, 0, len(#activities_for)-1)
declare #sql nvarchar(MAX) = N'
select COMPANYNAME,
<activities>
From
(select c.COMPANYNAME, a.ACTIVITYNAME,
(case
when ca.ACTIVITYID is not null and ca.COMPANYID is not null then 1
else 0
end) as STATUS
from #CompanyMaster c
cross join #ActivityMaster a
left join #CompanyActivities ca on ca.COMPANYID = c.COMPANYID and a.ACTIVITYID = ca.ACTIVITYID) p
pivot
(
sum(STATUS) for ACTIVITYNAME IN (<activities_for>)
) as pvt
'
set #sql = replace(#sql, '<activities>', #activities)
set #sql = replace(#sql, '<activities_for>', #activities_for)
print #sql
exec sp_executesql #sql
drop table #CompanyMaster
drop table #ActivityMaster
drop table #CompanyActivities