Postgresql约束 [英] Postgresql constraint

问题描述

我似乎无法得到这个权利，我试图修改一个字段是一个外键，级联删除...我做错了什么？

  ALTER TABLE my_table 
 ADD CONSTRAINT $ 4 
 FOREIGN KEY my_field 
 REFERENCES my_foreign_table 
 ON DELETE CASCADE; 
  

解决方案

如果您发布错误消息，但是我认为你只是缺少括号：

pre $ ALTER TABLE my_table
添加约束条件my_fk
FOREIGN KEY （my_field）
REFERENCES my_foreign_table
ON DELETE CASCADE;


I cannot seem to get this right, I am trying to modify a field to be a foreign key, with cascading delete... what am i doing wrong?

ALTER TABLE my_table 
ADD CONSTRAINT $4 
FOREIGN KEY my_field 
REFERENCES my_foreign_table 
ON DELETE CASCADE;

解决方案

It would help if you posted the error message. But I think you are just missing the parenthesis:

ALTER TABLE my_table 
ADD CONSTRAINT my_fk 
FOREIGN KEY (my_field) 
REFERENCES my_foreign_table 
ON DELETE CASCADE;

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