Picking rows in SAS based on a specific value in a specific column

So I'm working with a data set that has millions of rows. I'm trying to cut down the number of rows, so that I can merge this data set and another data set by zipcode.

What I'm trying to do is take a specific column "X6" and search through it for the value of "357". Then every row that has that value I want to move into a new data set.

I'm assuming that I'm going to have to use some form of if/then statement, but I can't get anything to work successfully. If needed I can post a snapshot of some of my data or what SAS code I currently have. I've seen other things that are similar, but none of them involve SAS.

Thanks for all of your help in advanced.