尝试插入一些数据和一个递增的数字作为id（oracle db）

Question

I'm trying to insert data in my table1 that looks like this : id, value1, value2..

id being the primary key. I have an insert statement looking like this:

insert into table1 (id,value1,value2..)
    select ([*],value1, value2 ..) 
    from table2 

Now I want to have an incrementing number starting at 1 to be inserted into id from table1. What do I need to write into * to make this work?

Answer 1

In Oracle 12C, you can define id as a generated column. Here is an article on the subject.

In earlier versions of Oracle, I define a sequence:

create sequence table1_sequence;

You can use it directly in the insert :

insert into table1 (id,value1,value2..)
    select table1_sequence.nextval, value1, value2 ..
    from table2 ;

Or, what I normally do, is create an insert trigger to set the id automatically for any insert.

If you are only loading the table once, you can do the quicker-and-dirtier:

insert into table1 (id,value1,value2..)
    select row_number() over (order by ?), value1, value2 ..
    from table2 ;

The order by is in case you want the ids in a particular order.

Or, you can simply use:

insert into table1 (id,value1,value2..)
    select rownum, value1, value2 ..
    from table2 ;

Answer 2

There is no such thing as "auto_increment" or "identity" columns in Oracle as of Oracle 11g. However, you can model it easily with a sequence and a trigger:

 CREATE SEQUENCE id_seq START WITH 1;

Trigger definition:

CREATE OR REPLACE TRIGGER table1_tir 
BEFORE INSERT ON table1
FOR EACH ROW
BEGIN
  SELECT id_seq.NEXTVAL
  INTO   :new.id
  FROM   dual;
END;

IDENTITY column is available on Oracle 12c:

create table table1(
    id NUMBER GENERATED by default on null as IDENTITY,
    value1 VARCHAR2(10),
    value2 VARCHAR2(10)
 );