I have three tables as below:
First Table Second Table Third Table
Name PIN Id City City_id
David 1948 1 Roma 3
Susan 1245 2 Berlin 2
Jack 1578 3 New York 3
Hans 1247 2
Rose 8745 1
I want to merge first and second table according to third table. Result will be: Person
Name PIN City
David 1948 New York
Susan 1245 Berlin
Jack 1578 New York
Hans 1247 Berlin
Rose 8745 Roma
Firsty I can merge second and third table and then merge the result table with first table but I want to solve this problem without a medium table. How can I handle this? How can I combine first table's rows in sequence with a specified row in second table according to third table?
You would need a fourth table, PersonCity, with PersonID and CityID to link together. Think of relational databases like a grid (spreadsheet, roads). If you're going North and the street you want to get on is parallel (think |^| |^|) you're gonna need to use a different road that links the two. Currently, you have no such path.
The short answer is that your tables are not adequate for the task, what you need is along the lines of:
Table_1 Table_2 Table_3
Id Name PIN Id City Name_id City_id
1 David 1948 1 Roma 1 3
2 Susan 1245 2 Berlin 2 2
3 Jack 1578 3 New York 3 3
4 Hans 1247 4 2
5 Rose 8745 5 1
Then you can do your query as follow:
SELECT T1.Name, T1.PIN, T2.City
FROM Table_1 T1 LEFT JOIN Table_3 T2 ON T1.Id = T3.Name_id
LEFT JOIN Table_2 ON T3.City_id = T2.Id
ORDER BY T1.Name
Or you could ORDER BY City, name
I have good news and bad news.
The good news, Given the tables the way they were originally specified, in Oracle, this will give you something that looks like what you are asking:
---
--- Pay attention, This looks right but it is not!
---
select name,pin,city from
( select name,pin,rownum rn from first ) a,
( select city,id from second) b,
( select id,rownum rn from third ) c
where
a.rn=c.rn AND
b.id=c.id;
NAME PIN CITY
-------------------- ---- --------------------
Rose 8745 Roma
Susan 1245 Berlin
Hans 1247 Berlin
David 1948 New York
Jack 1578 New York
The bad news is this does not really work and is cheating. You will get results but they may not be what you would expect and they won't necessarily be consistent.
The database orders records in its own order. If you don't specify an order by clause, you get what they give you, which may not be what you want. This is cheating because Oracle does not REALLY support using rownum in this way because you can't bet on what you will get. This won't work in most other databases.
The only correct way is what #daShier gave, where you have to add something, say, ID, to allow connecting the rows in the order you want.
Related
I am trying to query in MS SQL and I can not resolve it. I have a table employees:
Id Name Surname FatherName MotherName WifeName Pincode isChild
-- ------- ------- ---------- ---------- -------- ------- -------
1 John Green James Sue null 101011 1
2 Michael Sloan Barry Lilly null 101011 1
3 Sally Green Andrew Molly Jemi 101011 1
4 Barry Sloan Soul Paul Lilly 101011 0
5 James Green Ned White Sue 101011 0
I want a query that selects rows where the father name and mother name of child matches with name and wife name. For the example table, where I want to return the result of rows where father and mother name matches the name and wife name column. For eg. id=1, where John's father name James and mother name Sue matches with id 5 which returns James as first name and Sue as wife name. So my query should return (this is my expected result)
Id Name Surname FatherName MotherName WifeName Pincode isChild
-- ------- ------- ---------- ---------- -------- ------- -------
5 James Green Ned White Sue 101011 0
4 Barry Sloan Soul Paul Lilly 101011 0
I tried with the below query but it checks for James only. How to change my query so that it checks all the names and returns the expected result.
select * FROM employees
where first_name like '%James%'
and wife_name like '%Sue%'
and pincode=101011;
Any tips on this will be really helpful. I am new to joins, need help on writing self join to get the result.
…
select *
from thetable as p -- the parent/father
where exists -- with one child at least
(
select *
from thetable as c
where c.fathername = p.name
and c.mothername = p.wifename
-- lastname?
)
Too long for a comment, but also not intended as a slam against what you are working with. Please take as constructive criticism.
Aside from VERY POOR DESIGN on the table content, getting that corrected before you get too deep into whatever you are working should be done first. A more typical design might be having a table of people. Now, to get the relationships you could do a couple ways. One is that on each individual person's record, you add 2 additional IDs. FatherID, MotherID. These IDs would join directly back to the child vs hard strings to match against. Take a surname like Smith or Jones. Then, look at the many instances of a "John Smith" may exist, yes a lot, and lower probability of finding a matching wife's name of Sue, Mary or whatever else name. But even that could lead to multiple possibilities. Yes, you are adding a PIN, but even a computer can generate a random pin of 1234.
By having the IDs, there is NO ambiguity of who the relationship is with.
If the data were slightly altered to something like
Id Name Surname FatherID MotherID SpouseID
-- ------- ------- ---------- ---------- --------
1 John Green 5 6 null
2 Michael Sloan 4 3 null
3 Lilly Sloan null null 4
4 Barry Sloan null null 3
5 James Green 9 10 6
6 Sue Green 7 8 5
7 Bill Jones null null 8
8 Martha Jones null null 7
9 Brian Green null null 10
10 Beth Smith-Green null null 9
So, in this modified example, you can see right away that ID#1 John Green has parents of Father (ID#5) is James and Mother (ID#6) is Sue. But even from this, James is a child to Father (ID#9) Brian and Mother (ID#10) Beth. This scenario is showing to a grand-parent level capacity and that each of James and Sue are also children but to their respective parents. Sue's parents of the Jones surname.
For Michael Sloan, parents of #4 Barry, and #3 Lilly.
And I additionally added a spouse ID. This prevents redundancy of people's names copied all over. Then you can query based on the child's parent's respective IDs to find out vs a hopeful name LIKE guess.
So, even though not solving a relatively simple query, fixing the underlying foundation of your database and is relations will, long-term, help ease your querying in the future.
Try this:
SELECT
T2.*
FROM Employee T1
JOIN Employee T2 ON T2.Name = T1.FatherName
AND T2.WifeName = T1.MotherName
I have 2 tables and I am having trouble joining it to give me the desired output.
First table is called Future. It is future meetings I have.
Date Name Subject Importance Location
7/08/2020 David Work 1 London
7/08/2020 George Updates 2 New York
7/08/2020 Frank New Appointments 5 London
7/08/2020 Steph Policy 1 Paris
The second table is called Previous. It is previous meetings I have had.
Date Name Subject Importance Location Time Rating
1/08/2020 David Work 3 London 23.50 4
2/10/2018 David Emails 3 New York 18.20 3
1/08/2019 George New Appointments5 London 55.10 2
3/04/2020 Steph Dismissal 1 Paris 33.20 5
Now what I need to is to reference my previous table by name to see the previous meetings I have had with this person and I want all the data from the Previous Table there. I also need to limit it to only showing maximum 5 previous meetings with each person.
Date Name Subject Importance Location Time Rating
7/08/2020 David Work 1 London - -
1/08/2020 David Work 3 London 23.50 4
2/10/2018 David Emails 3 New York 18.20 3
7/08/2020 George Updates 2 New York - -
1/08/2019 George New Appointments5 London 55.10 2
The Name column will need to be a left join, but then i need to just do a regular join on the other columns. Also unsure how to limit the name results to a maximum of 5 of the same value. Thanks for your help in advance.
Basically, you want union all:
select m.*
from ((select Date, Name, Subject, Importance, Location, NULL as time, NULL as rating
from future
) union all
(select Date, Name, Subject, Importance, Location, time, rating
from previous
)
) m
group by name, date desc;
You can apply other conditions to this result. It is not clear what other conditions you really want, but this is a start.
I have tbl1 Structured like this
Name Type
====== =====
John 1
David 1
Jane 2
William 3
Alex 2
Ryan 1
And tbl2 structured like this
Index Type Job
1 1 Clean
2 1 Wash
3 2 Carry
4 2 Package
5 3 Sell
I would like to join record with matched Type, but each record in tbl1 only join once with one record in tbl2
Ie:
If
John is joined with Clean then David must be joined with Wash. Or if John is joined with Wash then David must be joined with Clean.
Doesn't matter if David is joined with Wash or Clean , I only need them to be joined with record that match the criteria and be joined ONCE.
I will make sure for each Type in 'tbl1' there will be equivalent amount of record in 'tbl2'
I mainly work on MS Access so Query on this environment would be the best~ Thank you all for reading.
Best regards
Try below query.
select name, (select TOP(1) job from tbl2 where tbl1.type = tbl2.type) from tbl1
Hope it help
I'm trying to update checkbox in record If record in table doesn't exist in another table.
Example data:
Table1:
111 John Davies
222 Mike Johnson
333 Allen Mckenzie
Table2:
000 John Jackson
222 Laura Kent
444 Paul Saint
I want to update only records, that have all fields different together, so in other words - each field doesn't exist. In my example result for this would be:
444 Paul Saint
I've tried with NOT IN, LEFT JOIN, INNER JOIN, but can't figure out correct clause because I need to update checkbox - so clause MUST Involve UPDATE.
Any ideas ?
I think something like this should work:
Update Table1
SET Checkbox = True
WHERE NOT EXISTS(SELECT 1
FROM Table2
WHERE table1.id=table2.id
OR table1.name=table2.name
or table1.surname=table2.surname)
I try to googling for this issue and still couldn't find the solution.
I have 2 column to combine like below:
First table:
ID Name Item
42 america 1433
42 america 1695
42 america 1234
8 london 1433
8 london 1705
8 london 1432
Second table:
ID CreatedBy
42 John
42 Erica
8 Amy Song
8 Alfred
If I just join both table it will become like this:
ID Name Item CreatedBy
42 america 1433 John
42 america 1695 John
42 america 1234 John
42 america 1433 Erica
42 america 1695 Erica
42 america 1234 Erica
8 london 1433 Amy Song
8 london 1705 Amy Song
8 london 1432 Amy Song
8 london 1433 Alfred
8 london 1705 Alfred
8 london 1432 Alfred
Column Created By is only related to ID, and not related to Name and Item.
I just want to insert CreatedBy as a new column into first table that only linked to ID, so the expected result will be like below.
Is there any way I could get result like this?
ID Name Item CreatedBy
42 america 1433 John
42 america 1695 Erica
42 america 1234 NULL
8 london 1433 Amy Song
8 london 1705 Alfred
8 london 1432 NULL
Let say we change second table like this:
Second table:
ID CreatedBy
42 John
8 Amy Song
Result will be like this:
ID Name Item CreatedBy
42 america 1433 John
42 america 1695 NULL
42 america 1234 NULL
8 london 1433 Amy Song
8 london 1705 NULL
8 london 1432 NULL
I really apreacite for your help, and thank you in advanced masta.
NOTE: Column CreatedBy is the independent column that only relate to ID and not relate to Name and Item.
So, I will answer you even though some guys that discussed it here on comments may disagree as there is no a proper logic to your problem.
It is important to note that this answer is for this SPECIFIC case if it won't get you the right data for a larger dataset you have to provide more info on it.
What I did:
I've created a subset from the first set ordering it (and indexing it, window function) by the name then I created another subset from the second set ordering it by the id so, i have:
select id, name, item, row_number() over (partition by name order by name) idx from tablea
And
select id, createdby, row_number() over (partition by id order by id) idx from tableb
Then I LEFT JOIN the tablea with tableb by the id and the order created colum idx so
select a.id, a.name, a.item, b.createdby
from (select id, name, item, row_number() over (partition by name order by name) idx from tablea) a
left join
(select id, createdby, row_number() over (partition by id order by id) idx from tableb) b
on (a.id = b.id and a.idx=b.idx)
order by a.name
The order by is just to get the result as you asked on your question.
See it here: http://sqlfiddle.com/#!3/7ef70/3
For your second sample data: http://sqlfiddle.com/#!3/675625/1