Dont know why anyone is downvoting this, this is absolutely true, and its even worse because the subset might work differently with the same keywords due to the

Dont know why anyone is downvoting this, this is absolutely true, and its even worse because the subset might work differently with the same keywords due to the underlying optimizer differences. This makes code you wrote in two different engines with the same syntax run vastly differently. Only if you are writing basic queries is the ansi sql promise realized.