Relational algebra is used for SQL language and the reason why is because it can be used for formal languages. Examples of relational algebra would be multiple sets such as college for one set and the attributes cName, state, and enrollment. Then students for the second set and its attributes sID, sName, GPA, and sizeHS. For the third set it would be apply and the attributes for that set would be sID, cName, major, and decisions. The other part that’s talked about in the video is the simplest query. What a simplest query is relation name that uses operators to filter, slice, and combine. Visually it would look like a chart.
There is a difference between relational algebra and SQL and that would be, and the difference is that in relational algebra there will never be more than two rows with the same exact values. With SQL the whole point for it is that it is used for multiple sets and duplicate values are removed. The other thing that is talked about is the union operator and it is used to combine information in vertical columns. With union operators they can be used to remove values in another relation. Another thing as well is that the rename operator reassigns the schema and is useful to combine two relations.