SQL insert into table by select from dual table

Question

Given the following create table SQL (which works fine):

CREATE TABLE blah (CAT, BUSINESS_NR, TIME_A, VERSION, SOME_CODE) AS
SELECT 'ABC',   123,    TIMESTAMP '2009-02-19 00:00:00 UTC',    1,  'OPP' FROM DUAL UNION ALL
SELECT 'GHI',   357,    TIMESTAMP '2020-08-16 00:00:00 UTC',    4,  'FFF' FROM DUAL UNION ALL
SELECT 'GHI',   357,    TIMESTAMP '2020-10-16 00:00:00 UTC',    5,  'ZZZ' FROM DUAL;

I have to switch now to an insert stmt, because table blah is created already.

My approach:

INSERT INTO blah (CAT, BUSINESS_NR, TIME_A, VERSION, SOME_CODE) 
select 
(         
SELECT 'ABC',   123,    TIMESTAMP '2009-02-19 00:00:00 UTC',    1,  'OPP' FROM DUAL UNION ALL
SELECT 'GHI',   357,    TIMESTAMP '2020-08-16 00:00:00 UTC',    4,  'FFF' FROM DUAL UNION ALL
SELECT 'GHI',   357,    TIMESTAMP '2020-10-16 00:00:00 UTC',    5,  'ZZZ' FROM DUAL
) from dual;

failed with error:

ORA-00913

What could I try?

Answer 1

You are using a subquery as a selected column, which is allowed, but the subquery must return only one row and one column .

So this is a valid syntax

select 
( SELECT 'ABC'  FROM DUAL ) 
from dual

But your subquery returns three rows and five column, which is not acceptable and leads to ORA-00913: too many values

What you may do is to use the subquery in the FROM clause. This is valid syntax:

INSERT INTO blah (CAT, BUSINESS_NR, TIME_A, VERSION, SOME_CODE) 
select * 
FROM
(         
SELECT 'ABC',   123,    TIMESTAMP '2009-02-19 00:00:00 UTC',    1,  'OPP' FROM DUAL UNION ALL
SELECT 'GHI',   357,    TIMESTAMP '2020-08-16 00:00:00 UTC',    4,  'FFF' FROM DUAL UNION ALL
SELECT 'GHI',   357,    TIMESTAMP '2020-10-16 00:00:00 UTC',    5,  'ZZZ' FROM DUAL
);

In this simple case (as pointed out by others) you may get rid of the main query at all.

Answer 2

You don't need the extra SELECT :

INSERT INTO blah (CAT, BUSINESS_NR, TIME_A, VERSION, SOME_CODE)         
    SELECT 'ABC', 123, TIMESTAMP '2009-02-19 00:00:00 UTC', 1, 'OPP' FROM DUAL UNION ALL
    SELECT 'GHI', 357, TIMESTAMP '2020-08-16 00:00:00 UTC', 4, 'FFF' FROM DUAL UNION ALL
    SELECT 'GHI', 357, TIMESTAMP '2020-10-16 00:00:00 UTC', 5, 'ZZZ' FROM DUAL;

The problem with your query is that you have subqueries that return more than one column. That is not generally allowed in SQL.