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Remove duplicate from left join

Posted on 2016-09-06
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Last Modified: 2016-09-06
HEllo,

I am doing two left join to a main table and I am alway getting duplicate.
I have tried many  different query buy I always get duplicates, I have simplify what I want below

Tperson                                   TFruitPerson                                          Tpersonveggie            
idperson        Name            idFruitPerson   Fruit      idperson                  idVeggiePerson      Veggie      idperson
1                      John            1                         Apple              1                      1                            lettuce       1
2                      Paul            2                         coconut      1                          2                               Spinash       2
3                      Frank            3                         cherry              2                    3                               avocado      2
                        
                                                      
                                                      
                                                      
Result desired                                                      
Name      Fruit          Veggie                                          
John      Apple          Lettuce                                          
John      Coconut                                                
Paul        Cherry          Spinash                                          
Paul                                 avocado                                          
Frank      apple                                                
Frank      Cherry
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Question by:arnololo123
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6 Comments
 
LVL 41

Expert Comment

by:Sharath
ID: 41786827
In your example, I don't find Frank having any fruits or veggies.
You can try like this.
select name,
       case when rn1 >= rn2 then Fruit end as Fruit, 
	   case when rn2 >= rn1 then Veggie end as Veggie
  from Tperson p
  left join (select *,row_number() over (partition by idperson order by idFruitPerson) rn1 from TFruitPerson) f on p.idperson = f.idperson
  left join (select * , row_number() over (partition by idperson order by idVeggiePerson) rn2 from Tpersonveggie) v on p.idperson = v.idperson

Open in new window


Tested with your sample data.
declare @Tperson table(idperson int, name varchar(10))
declare @TFruitPerson table(idFruitPerson int, Fruit varchar(10),idperson int)
declare @Tpersonveggie table(idVeggiePerson int, Veggie varchar(10),idperson int)

insert @Tperson values (1,'John'),(2,'Paul'),(3,'Frank')
insert @TFruitPerson values (1,'Apple',1),(2,'coconut',1),(3,'cherry',2)
insert @Tpersonveggie values (1,'lettuce',1),(2,'Spinash',2),(3,'avocado',2)

select name,
       case when rn1 >= rn2 then Fruit end as Fruit, 
	   case when rn2 >= rn1 then Veggie end as Veggie
  from @Tperson p
  left join (select *,row_number() over (partition by idperson order by idFruitPerson) rn1 from @TFruitPerson) f on p.idperson = f.idperson
  left join (select * , row_number() over (partition by idperson order by idVeggiePerson) rn2 from @Tpersonveggie) v on p.idperson = v.idperson

/*
name	Fruit	Veggie
John	Apple	lettuce
John	coconut	NULL
Paul	cherry	Spinash
Paul	NULL	avocado
Frank	NULL	NULL
*/

Open in new window

0
 
LVL 42

Expert Comment

by:pcelba
ID: 41786830
To obtain the result desired is impossible because there is no connection between Frank and Cherry as visible in the previous answer.
0
 

Author Comment

by:arnololo123
ID: 41786837
sorry I forget to add in the Table TfruitPerson   Franck with Cherry and apple.
0
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Author Comment

by:arnololo123
ID: 41786862
Sharath, thanks but it does not work properly if a person has 2 fruits AND 2 veggies, I am getting a result of 4 lines instead of 2.
0
 
LVL 41

Accepted Solution

by:
Sharath earned 500 total points
ID: 41786893
try this.
declare @Tperson table(idperson int, name varchar(10))
declare @TFruitPerson table(idFruitPerson int, Fruit varchar(10),idperson int)
declare @Tpersonveggie table(idVeggiePerson int, Veggie varchar(10),idperson int)

insert @Tperson values (1,'John'),(2,'Paul'),(3,'Frank')
insert @TFruitPerson values (1,'Apple',1),(2,'coconut',1),(3,'cherry',2)
insert @Tpersonveggie values (1,'lettuce',1),(2,'Spinash',2),(3,'avocado',2),(4,'spinach',1),(5,'veg',1)

select *
  from @Tperson p
  left join (
select coalesce(f.idperson,v.idperson) idperson, Fruit,Veggie
  from (select *, row_number() over (partition by idperson order by idFruitPerson) rn1 from @TFruitPerson) f
  full join (select *,row_number() over (partition by idperson order by idVeggiePerson) rn2 from @Tpersonveggie) v on f.idperson = v.idperson and rn1=rn2) fv
  on p.idperson = fv.idperson
/*
idperson	name	idperson	Fruit	Veggie
1	John	1	Apple	lettuce
1	John	1	coconut	spinach
1	John	1	NULL	veg
2	Paul	2	cherry	Spinash
2	Paul	2	NULL	avocado
3	Frank	NULL	NULL	NULL
*/

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1
 

Author Closing Comment

by:arnololo123
ID: 41787061
awesome thank you
0

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