What is going on with this SQL PK/FK error?

Question

I am having an issue with my SQL code. I am creating two tables, one named Orders_For, and another named Result. Result should pull the "Date," and "Time" from Orders_For as foreign keys. These foreign keys from Orders_for are also Result's primary keys. Can someone please help point me in the right direction?

I am getting Error:

ORA-00955: name is already used by an existing object
00955. 00000 - "name is already used by an existing object"

Here is the code that is giving this and the result:

Code (Easier to understand in images):

--ORDERS_FOR(OrdersForDate, OrdersForTime, PhysicianID, TestNumber, TestName, PatientID)

CREATE TABLE ORDERS_FOR(
    
OrdersForDate VARCHAR(50),
    
OrdersForTime VARCHAR(50),
    
O_PhysicianID CHAR(5),
    
O_TestNumber CHAR(5),
    
O_TestName VARCHAR(45),
   
O_PatientID CHAR(10),
    

CONSTRAINT Orders_ForPK_ok PRIMARY KEY(OrdersForDate,OrdersForTime,O_PhysicianID,O_TestNumber,O_TestName,O_PatientID),
    CONSTRAINT Orders_ForFK FOREIGN KEY(O_PhysicianID)
        REFERENCES PHYSICIAN(PhysicianID),
    CONSTRAINT Orders_ForFK_tol FOREIGN KEY(O_TestNumber,O_TestName)
        REFERENCES TEST(TestNumber,TestName),
    --CONSTRAINT Orders_ForFK FOREIGN KEY(O_TestName)
      -- REFERENCES TEST(TestName),
    CONSTRAINT Orders_ForFK_toll FOREIGN KEY(O_PatientID)
        REFERENCES PATIENT(PatientID)
    );
        
--RESULT(Date, Time, Result)
CREATE TABLE RESULT(
   ResultDate VARCHAR(50),
   ResultTime VARCHAR(50),
   ResultGiven VARCHAR(100),
   CONSTRAINT ResultPK_o PRIMARY KEY(ResultDate,ResultTime),
   CONSTRAINT ResultFK_tol FOREIGN KEY(ResultDate,ResultTime)
        REFERENCES ORDERS_FOR(OrdersForDate,OrdersForTime)
  --CONSTRAINT ResultFK_n2 FOREIGN KEY(ResultTime)
       --REFERENCES ORDERS_FOR(OrdersForTime)
    );

And here is the Script Output:

Table ORDERS_FOR created.

Error starting at line : 86 in command -
CREATE TABLE RESULT(
ResultDate VARCHAR(50),
ResultTime VARCHAR(50),
ResultGiven VARCHAR(100),
CONSTRAINT ResultPK_o PRIMARY KEY(ResultDate,ResultTime),
CONSTRAINT ResultFK_tol FOREIGN KEY(ResultDate,ResultTime)
REFERENCES ORDERS_FOR(OrdersForDate,OrdersForTime)
--CONSTRAINT ResultFK_n2 FOREIGN KEY(ResultTime)
--REFERENCES ORDERS_FOR(OrdersForTime)
)

Error report -
ORA-02270: no matching unique or primary key for this column-list 02270. 00000 - "no matching unique or primary key for this column-list"
*Cause: A REFERENCES clause in a CREATE/ALTER TABLE statement gives a column-list for which there is no matching unique or primary key constraint in the referenced table.
*Action: Find the correct column names using the ALL_CONS_COLUMNS catalog view

These are also attached in the images.

code

result

Answer 1

A foreign key references a primary (or unique) key. Ie for a row in the child table there is exactly one related row in the parent table.

You want a foreign key on (ResultDate, ResultTime) . But this is not a primary or unique key in the parent table ORDERS_FOR . There can be many rows for the same date and time, because the two columns are only part of the primary key.