Datalog was further refined over time, As well as in 1989, the language was standardized because of the Intercontinental Firm for Standardization (ISO). The standardization gave the language a way more formal specification, which served in its broader adoption. Datalog is unique in that it is based on procedures in https://datalog522097.humor-blog.com/33008008/helping-the-others-realize-the-advantages-of-datalog-5