SQL'加入'2个主键到1

Question

I have 2 tables:

PrimKey
001
002

And:

ID | ForeignKey
a  | 001
b  | 002
c  | 002

I want to delete, let's say, row 002 and 'bind' all 002 foreign keys to 001, so it will look like:

PrimKey
001

And:

ID | ForeignKey
a  | 001
b  | 001
c  | 001

FK constraints do not allow me to do UPDATE + DELETE. Any tip where to dig?

Answer 1

You have to do it from the other direction. Change the rows in the second table to point to a different PK in the first table; then when there are no references to row002, you can delete it.

Answer 2

您也可以尝试begin transaction ， update ， delete和commit 。

Answer 3

if you have no control over the database schema, then you must manually delete as pointed out by Jeremy.

If you do have control, you can add a foreign key relationship between the tables and add a "cascade delete" constraint in the relationship detail. You do this by going to the table design of the table with foreign keys and right-clicking to choose "Relationships." Then you choose "Add" and go to the section for defining the table and columns. Click the button with the three dots and you will be able to choose the parent table for the relationship and then you can select the columns for creating the relationship. Finally, in the relationships screen you locate the insert/update specification section to indicate "cascade" on delete. (There is an alter table statement for this, too, but sometimes it's just faster to use the GUI.)