Question

I have a row of data in a table:

Key | Val1 | Val2
----+------+-----
1   | A    | B

I would like to copy this row, but assign each new row a different key (actually a foreign key) from a list:

New keys
--------
2
3
4

This list can easily be obtained via a query. After the duplication, the table should look like this:

Key | Val1 | Val2
----+------+-----
1   | A    | B
2   | A    | B
3   | A    | B
4   | A    | B

So far, all I’ve come up with is this:

INSERT INTO table (Key, Val1, Val2) (
    SELECT '2' AS Key, Val1, Val2 FROM table WHERE Key='1'
);

This works, but of course it only copies one row at a time. Is there a way to copy all the rows at once?

I’m using Oracle if it makes a difference.

Answer 1

You can use SELECT .. FROM DUAL to make up values, and you can use UNION ALL to combine multiple rows into a single result. There are various other ways to create a result set such as a Recursive Common Table Expression.

INSERT INTO table (Key, Val1, Val2)
SELECT d.newKey, t.Val1, t.Val2
FROM table t
cross join (select 2 NewKey from dual union all
            select 3 NewKey from dual union all
            select 4 NewKey from dual) d;

If your new keys come from a subquery, it’d be even easier, e.g.

INSERT INTO table (Key, Val1, Val2)
SELECT d.FKey, t.Val1, t.Val2
FROM table t
cross join (select FKey
            from SomeOtherTable
            Where ......) d;

However, do note that because you’re copying FROM table and INTO table, you’ll replicate ALL the records from table at the same time for each foreign key.