an umbrella term that combines architecture tools, databases, analytical tools, applications, and methodologies it's a content free expression, so it means different things to different people
an umbrella term that combines architectures, tools, data-bases, analytical tools, applications, and methodologies with main objective to enable interactive to data.
the relational model of data is based on the concept of a relation  proposed in 1970 by e.f. codd (ibm), first commercial system in 1981-82.