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0

I have 2 collections in MongoDB 3.4.7:

Collection1
Id: 54648364848
Internal Code: 50

Collection2
Id: 54648364848
Quantity: -10

Would you like to update the Quantity field of Collection2 using the Internal Code field of Collection1? Given that the field they have in common is the Id, but I do not want to specify it in the sentence (because in the system in question, the ID is a gigantic numbering). A rude example of reasoning in SQL:

update Collection2
set Collection2.Quantity = 25
where Collection1.Id = Collection2.Id and
             Collection1.Internal Code = 50

mongodb

share|improve this question

asked Mar 28 at 3:42

WashingtonWashington

1

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  MongoDB does not support "join statements" in updating. You update via the "foreign collection" you actually want to update and not based on conditions in the master collection. If you need to do that, you can query the master collection for it's condition, and then feed to the "foreign update" using $in for the related Id values. So two statements to the server instead of one. But in truth, if you need to do that it's more of an indicator of bad design. Change the design or use an RDBMS.
  
  – Neil Lunn
  Mar 28 at 9:50
  
  

  
  
  
  

add a comment | 

0

I have 2 collections in MongoDB 3.4.7:

Collection1
Id: 54648364848
Internal Code: 50

Collection2
Id: 54648364848
Quantity: -10

Would you like to update the Quantity field of Collection2 using the Internal Code field of Collection1? Given that the field they have in common is the Id, but I do not want to specify it in the sentence (because in the system in question, the ID is a gigantic numbering). A rude example of reasoning in SQL:

update Collection2
set Collection2.Quantity = 25
where Collection1.Id = Collection2.Id and
             Collection1.Internal Code = 50

mongodb

share|improve this question

asked Mar 28 at 3:42

WashingtonWashington

1

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  MongoDB does not support "join statements" in updating. You update via the "foreign collection" you actually want to update and not based on conditions in the master collection. If you need to do that, you can query the master collection for it's condition, and then feed to the "foreign update" using $in for the related Id values. So two statements to the server instead of one. But in truth, if you need to do that it's more of an indicator of bad design. Change the design or use an RDBMS.
  
  – Neil Lunn
  Mar 28 at 9:50
  
  

  
  
  
  

add a comment | 

I have 2 collections in MongoDB 3.4.7:

Collection1
Id: 54648364848
Internal Code: 50

Collection2
Id: 54648364848
Quantity: -10

Would you like to update the Quantity field of Collection2 using the Internal Code field of Collection1? Given that the field they have in common is the Id, but I do not want to specify it in the sentence (because in the system in question, the ID is a gigantic numbering). A rude example of reasoning in SQL:

update Collection2
set Collection2.Quantity = 25
where Collection1.Id = Collection2.Id and
             Collection1.Internal Code = 50

mongodb

share|improve this question

asked Mar 28 at 3:42

WashingtonWashington

1

Collection1
Id: 54648364848
Internal Code: 50

Collection2
Id: 54648364848
Quantity: -10

update Collection2
set Collection2.Quantity = 25
where Collection1.Id = Collection2.Id and
             Collection1.Internal Code = 50

share|improve this question

asked Mar 28 at 3:42

WashingtonWashington

1

share|improve this question

asked Mar 28 at 3:42

WashingtonWashington

1

asked Mar 28 at 3:42

WashingtonWashington

1

asked Mar 28 at 3:42

WashingtonWashington

1