SQL(SQL/Oracle) insert value from a select statement using sequence

Question

I want to insert (user_id) value from a select statement like below without identity column. Currently this query doesn't follow the sequence number in order. Kindly advise.

https://dbfiddle.uk/?rdbms=oracle_18&fiddle=195728e48cc8a5a0047fec8837e9f217

Answer 1

This is answering the original version of the question.

If you are asking can you have identical SQL statements to use a sequence in SQL Server and in Oracle then, no, you cannot.

In Oracle, the syntax is:

INSERT INTO b_user ( user_id /*, ... */ )
  VALUES ( b_user__user_id__seq.NEXT_VAL /*, ... */ );

In SQL Server, the syntax is:

INSERT INTO b_user ( user_id /*, ... */ )
  VALUES ( NEXT VALUE FOR b_user__user_id__seq /*, ... */ );

---

In Oracle, you could wrap the call to the sequence in a function:

CREATE FUNCTION get_next_b_user_id RETURN INT
IS
BEGIN
  RETURN b_user__user_id__seq.NEXTVAL;
END;
/

Then you could use:

INSERT INTO b_user ( user_id /*, ... */ )
  VALUES ( get_next_b_user__id__seq() /*, ... */ );

However, in SQL server you cannot use a sequence in user-defined functions so that approach in Oracle cannot be replicated.

---

So, in short, you are going to have to use different SQL statements for the different databases if you are using a sequence.

If you want to use an IDENTITY column then you can get the same syntax in both.

In Oracle:

CREATE TABLE b_user (
  user_id      INT
               GENERATED ALWAYS AS IDENTITY,
  user_name    VARCHAR(250),
  user_email   VARCHAR(250),
  user_address VARCHAR(250),
  user_city    VARCHAR(50),
  user_state   VARCHAR(5),
  user_country VARCHAR(5),
  user_zip     VARCHAR(10)
);

and in SQL Server:

CREATE TABLE b_user (
  user_id      INT IDENTITY(1,1),
  user_name    VARCHAR(250),
  user_email   VARCHAR(250),
  user_address VARCHAR(250),
  user_city    VARCHAR(50),
  user_state   VARCHAR(5),
  user_country VARCHAR(5),
  user_zip     VARCHAR(10)
)

Then, in both databases, you can use the statement:

insert into b_user (
  user_name,
  user_email,
  user_address,
  user_city,
  user_state,
  user_country,
  user_zip
) values (
  'Alice',
  'alice@example.com',
  'A house',
  'A city',
  'STATE',
  'ABC',
  'ZZ0123'
);

Oracle db<>fiddle and SQL Server db<>fiddle

Answer 2

one option is, if you know know that the column user_id has some values already inserted then when you create a sequence which you are going to use for that column

--example you start with 3 if you know 2 is the maximum value for that column.
CREATE SEQUENCE b_user__user_id__seq  start with 3 ;

It is better to have a primary key or unique constraint in that column.