How handle currval if nextval fails

Question

hi,
i have to insert the following rows in the table if
Insert into BOOK (BOOK_ID, CNT, ALT_CNT, ROW_INSERT_TMSTMP, ROW_LAST_UPDT_TMSTMP, BOOK_ID,VERSION)
SELECT SEQ_BOOK_ID.nextval, 50 , 500 ,sysdate,sysdate, '123456xyz' ,1 FROM DUAL WHERE NOT EXISTS (SELECT 1 FROM BOOK B WHERE b.BOOK_ID = '123456xyz' );
Insert into BOOK_OWNER (BOOK_OWNER_ID, BOOK_ID, USER_ID,VERSION)
SELECT SEQ_BOOK_OWNER_ID.nextval, SEQ_BOOK_ID.currval, '30327def',1 FROM DUAL WHERE NOT EXISTS (SELECT 1 FROM BOOK_OWNER AO WHERE AO.USER_ID= '30327def');
commit;
in above #1st statement checking if the value exists in book and inserting if the first insert fails the secound insert statement uses the "SEQ_BOOK_ID.currval" of the parent. if #1 insert fails how to handle the currval of the secound statement?
using oralce 10g

Answer 1

Hi,
[email protected] wrote:
also would like to know in anyof the condition the nextval will fail? i mean for some of the records insertion in getting the primery key violation.
like i am doing one time migration with huge data in to the database around 200 to 300 similar insert statements and some times i am getting the primery key voilation i suspect nextval is failing not able to figure it out.That sounds like some rows were entered with a primary key that was not generated by the sequence.
You should change the sequence so that it is generating numbers higher than anything already in the table.
First, find out what the highest id in the table is. For example:
SELECT  MAX (book_id)
FROM    book;Say this tells you that book_id=12345 is already in the table. Now find out how high the sequence is. For example:
SELECT  seq_book_id.NEXTVAL
FROM    dual;Say this returns 12000, which means you have to add 345 to the sequence.
You don't want to drop and re-create the sequence; that might make procedures invalid, or lose grants.
You could reference .NEXTVAL 345 times, or you could say:
ALTER SEQUENCE  seq_book_id  INCREMENT BY 345;
SELECT  seq_book_id.NEXTVAL
FROM    dual;
ALTER SEQUENCE  seq_book_id  INCREMENT BY 1;This assumes the sequence had originally been incrementing by 1.
The problem is liable to keep happening as long as the table is incremented without using the sequence.
You can add a trigger to guarantee that the sequence is used.