is insert into.. select statement transactional?

Question

do i need to use transaction to provide all or not proposition for the following insert process?

INSERT INTO table1 ( column1 , column2)
SELECT  col1, col2
FROM    table2  

expecting average row-count from table2 is around 150 and target database is ms sql server 2008 r2.

Answer 1

No, you don't need to. A single SQL statement is already in a transaction by default so there is no way that you will partually insert results or that results will be meanwhile moderated by another transaction. The fact that 2 tables are involved doesn't change the fact that a single SQL statement is used.