sql - 作成/挿入時に連番を追加 - Teradata

Question

Oracle では、このテーブルを作成する際に select で rownum を使用します。現在、teradata では、それを機能させることができないようです。3 つの列を一緒に使用しない限り、並べ替えて一意の値 (多くの重複) を持つことができる列はありません。

古い方法は次のようになります。

create table temp1 as 
  select
    rownum as insert_num,
    col1,
    col2,
    col3
  from tables a join b on a.id=b.id
;

Answer 1

これはあなたがそれを行う方法です：

create table temp1 as 
( 
   select
      sum(1) over( rows unbounded preceding ) insert_num
     ,col1
     ,col2
     ,col3
   from a join b on a.id=b.id
) with data ;

Answer 2

Teradata has a concept of identity columns on their tables beginning around V2R6.x. These columns differ from Oracle's sequence concept in that the number assigned is not guaranteed to be sequential. The identity column in Teradata is simply used to guaranteed row-uniqueness.

Example:

CREATE MULTISET TABLE MyTable
  (
   ColA INTEGER GENERATED BY DEFAULT AS IDENTITY
       (START WITH 1
        INCREMENT BY 20)
   ColB VARCHAR(20) NOT NULL
  )
UNIQUE PRIMARY INDEX pidx (ColA);

Granted, ColA may not be the best primary index for data access or joins with other tables in the data model. It just shows that you could use it as the PI on the table.

Answer 3

これも機能します：

create table temp1 as 
( 
   select
   ROW_NUMBER() over( ORDER BY col1 ) insert_num
   ,col1
   ,col2
   ,col3
   from a join b on a.id=b.id
) with data ;