Inserting multiple rows with sequence in Oracle

The restrictions on multitable inserts include:

• You cannot specify a sequence in any part of a multitable insert statement. A multitable insert is considered a single SQL statement. Therefore, the first reference to NEXTVAL generates the next number, and all subsequent references in the statement return the same number.

That isn't quite true - you can use a sequence, it just always gets the same value, so it can be useful to create parent and child records in one go by referring to the same sequence.

If you want to continue to use insert all you could work around that by using a non-deterministic function that gets the sequence value:

CREATE FUNCTION get_seq RETURN NUMBER IS
BEGIN
  RETURN postal_code_seq.nextval;
END;
/

INSERT ALL
  INTO POSTAL_CODE( postal_code,description)
    VALUES(get_seq,'Coimbatore')
  INTO POSTAL_CODE (postal_code,description)
    VALUES(get_seq,'Mumbai') SELECT * FROM DUAL;

2 rows inserted.

SELECT * FROM postal_code;

                            POSTAL_CODE DESCRIPTION        
--------------------------------------- --------------------
                                      1 Coimbatore          
                                      2 Mumbai              

But that's a bit awkward. You're probably better off using individual insert statements - using a multitable insert into a single table isn't really gaining you much anyway - or a trigger to set the unique column from the sequence, or a CTE/inline view to generate the values to insert.

I would use a before insert trigger to populate the key column (if no value has been supplied by the insert) instead of this method. Sequences do not work well with multi-table insert.

Instead of modifying your database objects you can simply rewrite the multitable INSERT ALL into a single INSERT with multiple rows concatenated by UNION ALL:

INSERT INTO postal_code
SELECT postal_code_seq.NEXTVAL, description
FROM
(
    SELECT 'Coimbatore' description FROM dual UNION ALL
    SELECT 'Mumbai'     description FROM dual
);

Note that the sequence must be called in an outer query. Using a sequence in the inner query looks like it could simplify the code but would raise the error "ORA-02287: sequence number not allowed here".