Delete the parent record

Question

hi all,
based on the thread i got the list of child tables.
Re: to find the tables which is having link with particular table.
no i have doubt in deletion process.
My ultimate aim is to delete the bl_det records.
let me explain with ex.
i have table
BL_DET --parent table with comp and ref as primary key
which is having child rec.
BL_CON --child of BL_DET(comp,ref) primary key comp,ref and serial
BL_CON_PCK --is child of BL_CON(comp,ref,serial) primary key comp,ref,serial,pck_gp_srl,gp_srl.
DELETE BL_CON_PCK
WHERE BCK_COMP = :GLOBAL.comp
AND BCK_REF = :parameter;
DELETE FROM BL_CON
WHERE BCR_COMP = :GLOBAL.comp
AND BCR_REF = :paramter
DELETE FROM BL_DET
WHERE BL_COMP = :GLOBAL.comp
AND BL_REF - :parameterwill delete the correct set of records.(my doubt area is delete statement written for the table BL_CON_PCK).
Please tell me if i am wrong.
Thanks..

Answer 1

(my doubt area is delete statement written for the table BL_CON_PCK).Cannot understand your doubt. What is your doubt, are you getting any error while executing your code?
To delete a record from parent table all child references must be deleted. So your delete statement appears right
-- How delete should progress
BL_CON_PCK >> BL_CON >> BL_DET
{code}
If you have created foreign constraint using ON DELETE CASCADE or ON DELETE SET NULL then you can straight away delete from parent table and all child references are deleted/set as null respectively. Read Oracle Documentation to see details
Short demonstration
{code:sql}
SQL> CREATE TABLE A(a1 NUMBER PRIMARY KEY , a2 NUMBER);
Table created
SQL>  CREATE TABLE B(b1 NUMBER PRIMARY KEY , a1 NUMBER);
Table created
SQL>  CREATE TABLE C(c1 NUMBER, b1 NUMBER);
Table created
SQL>  ALTER TABLE B ADD CONSTRAINT FK_B FOREIGN KEY (a1) REFERENCES A ON DELETE CASCADE;
Table altered
SQL>  ALTER TABLE C ADD CONSTRAINT FK_C FOREIGN KEY (b1) REFERENCES B ON DELETE CASCADE;
Table altered
SQL>  INSERT INTO A VALUES (1,2);
1 row inserted
SQL>  INSERT INTO B VALUES (3,1);
1 row inserted
SQL>  INSERT INTO C VALUES (4,3);
1 row inserted
SQL>  SELECT * FROM A;
        A1         A2
         1          2
SQL>  SELECT * FROM B;
        B1         A1
         3          1
SQL>  SELECT * FROM C;
        C1         B1
         4          3
SQL>  DELETE FROM A WHERE A1=1;
1 row deleted
SQL>  SELECT * FROM A;
        A1         A2
SQL>  SELECT * FROM B;
        B1         A1
SQL>  SELECT * FROM C;
        C1         B1
{code}