Math
Reading mathematical notation, from the primitives up. Not a course and not a proof — the aim is to be able to read a formula and say what it means.
- Sets, and why a table is oneThe marks for membership, subsets, size and the Cartesian product — and the one idea the rest of the series rests on: a database table is a set of tuples, which is what the word relational means.Lesson 1
- Functions, and why subscripts are functionsWhat the arrow in f from A to B means, why every column of a table is a function from a row to a value, and why a subscript is the same thing written differently.Lesson 2
- Sigma, and what it is really doingThe summation sign has exactly four parts, and every sigma you will ever meet has the same four.Lesson 3
- Nested sums, and the loop they describeTwo sigmas side by side are two nested loops.Lesson 4
- Products, quantifiers, grouping and joinsPi is sigma with multiplication and identical grammar.Lesson 5
- Reading a real formulaTaking the revenue formula apart mark by mark, the three checks worth running on any formula of that shape, a set of mixed exercises with no new notation, and a cheat sheet of everything in the series.Lesson 6