CODEWITHSUNDEEP
mysqlsqlforeign-keys
Delphine
Delphine

Reputation: 888

Is it possible to create a "foreign key pair" ? - SQL

I have 3 tables involved.I would like, in the third table, to ensure that a pair of keys in this table is present in the second one. 

CATEGORY  
idc

-

CHILD_CATEGORY 
idcc
c_category_id

-

PLACE_CHILD_CATEGORY
idp
p_category_id
p_child_category_id

I would like to know if I can create a link that ensures that.

PLACE_CHILD_CATEGORY(p_category_id, p_child_category_id) combination exists in CHILD_CATEGORY(idcc, c_category_id)

Where :

p_child_category_id == idcc

et

p_category_id == c_category_id

Any way to do that ?

Upvotes: 0

Views: 2478

Answers (1)

Rimas
Rimas

Reputation: 6024

ALTER TABLE PLACE_CHILD_CATEGORY
  ADD FOREIGN KEY PLACE_CHILD_CATEGORY_fk (p_category_id, p_child_category_id)
  REFERENCES CHILD_CATEGORY (c_category_id, idcc)

More info: Using FOREIGN KEY Constraints; ALTER TABLE Syntax

Upvotes: 2

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