Constraining child column to be between values in parent record

Question

I know there's not a declarative constraint to do this, but I am wondering what ideas people have for the best pattern to use.
I have a parent table ALPHA with columns ALPHA_ID, START_DATE and END_DATE.
Then I have a child table BETA with columns BETA_ID, ALPHA_ID and TRAN_DATE.
I would like to constrain that BETA.TRAN_DATE is between ALPHA.START_DATE and ALPHA.END_DATE. I'm reluctant to use a trigger because BETA will have many inserts.
I have considered creating a table ALPHA_DATE with columns ALPHA_ID, START_DATE, END_DATE and TRAN_DATE, with the first three columns as a foreign key to the same columns in ALPHA, and a CHECK constraint that (TRAN_DATE between START_DATE and END_DATE), then letting BETA(ALPHA_ID, TRAN_DATE) be a foreign key to ALPHA_DATE(ALPHA_ID, TRAN_DATE).
Thanks,
Matt

Answer 1

You could duplicate START_DATE and END_DATE into BETA table. Then:
SQL> CREATE TABLE ALPHA(
  2                     ALPHA_ID   NUMBER NOT NULL,
  3                     START_DATE DATE NOT NULL,
  4                     END_DATE   DATE NOT NULL
  5                    )
  6  /
Table created.
SQL> ALTER TABLE ALPHA
  2    ADD CONSTRAINT ALPHA_PK
  3      PRIMARY KEY(
  4                  ALPHA_ID
  5                 )
  6  /
Table altered.
SQL> ALTER TABLE ALPHA
  2    ADD CONSTRAINT ALPHA_UK1
  3      UNIQUE(
  4             ALPHA_ID,
  5             START_DATE,
  6             END_DATE
  7            )
  8  /
Table altered.
SQL> CREATE TABLE BETA(
  2                    BETA_ID    NUMBER NOT NULL,
  3                    ALPHA_ID   NUMBER NOT NULL,
  4                    TRAN_DATE  DATE NOT NULL,
  5                    START_DATE DATE NOT NULL,
  6                    END_DATE   DATE NOT NULL
  7                   )
  8  /
Table created.
SQL> ALTER TABLE BETA
  2    ADD CONSTRAINT BETA_FK1
  3      FOREIGN KEY(
  4                  ALPHA_ID,
  5                  START_DATE,
  6                  END_DATE
  7                 )
  8      REFERENCES ALPHA(
  9                       ALPHA_ID,
10                       START_DATE,
11                       END_DATE
12                      )
13  /
Table altered.
SQL> ALTER TABLE BETA
  2    ADD CONSTRAINT BETA_CK1
  3      CHECK(
  4            TRAN_DATE BETWEEN START_DATE AND END_DATE
  5           )
  6  /
Table altered.
SQL> INSERT
  2    INTO ALPHA
  3    VALUES(
  4           1,
  5           SYSDATE - 10,
  6           SYSDATE - 5
  7          )
  8  /
1 row created.
SQL> INSERT
  2    INTO BETA
  3    VALUES(
  4           1,
  5           1,
  6           SYSDATE - 7,
  7           SYSDATE - 10,
  8           SYSDATE - 5
  9          )
10  /
1 row created.
SQL> INSERT
  2    INTO BETA
  3    VALUES(
  4           1,
  5           1,
  6           SYSDATE - 2,
  7           SYSDATE - 10,
  8           SYSDATE - 5
  9          )
10  /
INSERT
ERROR at line 1:
ORA-02290: check constraint (SCOTT.BETA_CK1) violated
SQL> SY.