Facing Problem at work

I was assigned to a task. The task was to compile lots of data and to send it to the manager. I didn't have all the data. My colleagues including my boss had some and I had some. So, I collected all that data from each of my colleagues and compiled it. Finally, I sent the data to the manager but it turns out that there was an anomaly in some of the data.
So I was called out by the manager to provide justification for the anomaly. On examination, I could tell that the incorrect data was from my boss. He recorded the information incorrectly. Rather than mention my boss's name I took the blame. I admitted that I didn't crosscheck the data after compiling it all. The manager is a good person, or perhaps he was just being professional. He asked me to do it again and take the time to do it correctly. It made me sad. I needed to check & verify all the information from the beginning to fix the problem. My boss made the mistake, but I'm the one to pay for that. I could make a scene by pointing out his mistake, but that wouldn't solve anything and could bring more pressure and ill feeling to the situation. I like my boss. He is really good person, caring and an inspiration to me at work.
Sometimes the workplace suffocates me when situations like this occur. I want to save someone but don't want to bring danger to myself in the process as well. It is difficult for me to deal with this type of situation because looking after both parties at the same time is really hard.
I wish I knew how to be diplomatic like many other people seem to be.