All we need is an easy explanation of the problem, so here it is.
SQL is more than words:
CREATE TABLE "currency" ("id" NUMBER(10) NOT NULL, "currency" VARCHAR2(50) NOT NULL, "name" VARCHAR2(1020) DEFAULT NULL NULL, PRIMARY KEY("id"));
CREATE TABLE "user" ("id" NUMBER(10) NOT NULL, "name" VARCHAR2(1020) DEFAULT NULL NULL, "currency" VARCHAR2(50) DEFAULT NULL NULL, PRIMARY KEY("id"));
CREATE UNIQUE INDEX IDX_6956883FFF467AE9 ON "currency" ("currency");
ALTER TABLE "user" ADD CONSTRAINT FK_8D93D6496956883F6956883F695 FOREIGN KEY ("currency") REFERENCES "currency" ("currency");ORA-02270: no matching unique or primary key for this column-list
The column types are the same and unique index is added.
Why the FK cannot be added?
How to solve :
I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.
A unique index does not include a unique constraint.
Add the constraint and try again:
alter table "currency" add unique("currency") using index IDX_6956883FFF467AE9;
Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂