Check Constraint for Quantity column

Hi! I'm learning SQL Sever 2012, I'm doing some experiment. What I did is I created a check constraints in Quantity column from OrderItem table that will limit the maximum quantity value to 70, but there is already an existed row with higher value than 70. Now, when I save it, I get the post-save notification which I expected to happen. I just want to know if there is any solution except raising the maximum value for quantity. Any help would be appreciated.