Question

I have this statement:

INSERT INTO `alias`( `alias`, `ref_links_id`) VALUES ("3334",4)

And I get this error:

Cannot add or update a child row: a foreign key constraint fails 

(`bestr_main`.`alias`, CONSTRAINT `alias_ibfk_1` FOREIGN KEY (`ref_links_id`) 

REFERENCES `links` (`link_id`) ON DELETE CASCADE ON UPDATE CASCADE)

The alias table is connected to link table with a foreign key.
Why do I get this error when inserting a record?

I see now.. I tried to change the link between the keys to another table and I get this:

  1452 - Cannot add or update a child row: a foreign key constraint fails 

  (`bestr_main`.<result 2 when explaining filename '#sql-73c_38e0'>, CONSTRAINT 

 `#sql-73c_38e0_ibfk_1` FOREIGN KEY (`ref_links_id`) REFERENCES `refs` (`ref_id`) 

 ON DELETE CASCADE ON UPDATE C) 

What does that say?

Answer 1

Read the error

FOREIGN KEY (ref_links_id) REFERENCES links (link_id))

Means

`links`.link_id  (Parent)

`alias`.ref_links_id (Child)

and no child exist without parent. so first check parent table for the value which you are inserting into child table