Dr. Codd first described the relational model in a paper in Communications of the ACM (CACM 13 No 6; June 1970). Some more work followed up after that by other people, giving us normal forms and other things we have taken for granted for 50+ years.
I was looking at some postings on a SQL newsgroup. The original poster wanted help with a problem he had storing International Classification of Diseases (ICD) values. Alternatively, to put it more accurately, he needed help fixing the problems he had created for himself. The non-table he was creating had a single text column