Before this pull request, this code

var query=post.insert(post.id)
var select=user.select(user.id)
query.add(select)

would generate (properly quoted)

INSERT INTO post (id) (SELECT user.id FROM user)

Notice the parentheses around the SELECT clause. In many cases, this isn't a problem, but in Microsoft SQL server, when you try to add an ORDER BY clause onto your select, it is a syntax error when there are parentheses around the SELECT statement.

This pull request makes the above query generate:

INSERT INTO post (id) SELECT user.id FROM user

which is exactly what is generated when you write the query like:

var query=post.insert(post.id).select(user.id).from(user)

So it actually generates more consistent SQL regardless of the way that the query was constructed.