Insert into … values ( SELECT … FROM … )

Question

I am trying to INSERT INTO a table using the input from another table. Although this is entirely feasible for many database engines, I always seem to struggle t

Answer 1

select *
into tmp
from orders

Looks nice, but works only if tmp doesn't exists (creates it and fills). (SQL sever)

To insert into existing tmp table:

set identity_insert tmp on

insert tmp 
([OrderID]
      ,[CustomerID]
      ,[EmployeeID]
      ,[OrderDate]
      ,[RequiredDate]
      ,[ShippedDate]
      ,[ShipVia]
      ,[Freight]
      ,[ShipName]
      ,[ShipAddress]
      ,[ShipCity]
      ,[ShipRegion]
      ,[ShipPostalCode]
      ,[ShipCountry] )
      select * from orders

set identity_insert tmp off

Answer 2

This can be done without specifying the columns in the INSERT INTO part if you are supplying values for all columns in the SELECT part.

Let's say table1 has two columns. This query should work:

INSERT INTO table1
SELECT  col1, col2
FROM    table2

This WOULD NOT work (value for col2 is not specified):

INSERT INTO table1
SELECT  col1
FROM    table2

I'm using MS SQL Server. I don't know how other RDMS work.