I have a FK inside my table but i want to modify the parent table for the FK . so is there an alter command that can achieve this ? or i need to remove the FK and create a new one ? Thanks
Add this to your PK and it will automatically update all FKs for you:
ON UPDATE CASCADE
For full details, you can read this article .
EDIT Based on your comment, if you want to change the PK data type, it depends on the change:
To modify the data type, use the ALTER
command, the syntax is:
ALTER TABLE table_name
ALTER COLUMN column_name datatype
Examples:
ALTER TABLE table_name
ALTER COLUMN id NUMBER(10,2);
ALTER TABLE table_name
ALTER COLUMN id VARCHAR(20);
For full details, you can read this article .
Looks like you are looking for alter
statement but since you didn't mention exactly what you are looking to modify; I assume that you want to change column data type size. You can do something like this (an example; say you want to change size from 10 to 15)
alter table sample3
alter column name varchar(15)
EDIT:
In that case this is what you should be doing. You need to drop the existing constraint and recreate the constraint to point to TableC
alter table TableA
drop constraint your_FK_constraint_name
alter table TableA
add constraint constraint_name
FOREIGN KEY (column_name) references TableC(some other column name)
An Example:
alter table sample2
drop constraint FK__sample2__realnam__09DE7BCC
alter table sample2
add constraint FK__sample2__realnam
FOREIGN KEY (realname) references sample1(name)
Based on this comment, "now my current FK inside TableA is referring to another table primary key TableB. but i need my modify my current FK to refer to tableC instead of tableB ... this what i need (to modify the parent table for my FK)– "
The parent table is TableB. No action is required on that table.
On TableA, you have to:
in that order.
Edit Starts Here
Here is a link to the syntax,
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