Hi, everyone, I am a beginner in ruby programming and I have a minor question about data checking, if someone who could give me a suggestion that would be great. The system needs to prevent a duplicated record happened in database, the record is consisted of two fields which are column A and column B. Supposing a record has been saved in database that the A=1, B=1. Afterward, the same set of record can not be accepted again, for example, record: A=1, B=2 and A=2, B=1 both are acceptable. In other words, record: A=1, B=1 can not be saved in database. So how to check and prevent a new record that has the same columns with same values tend to be saved in database? Frank -- Posted via http://www.ruby-forum.com/.