In their definition of programming languages types, I'm not sure I see how SQL which they cateogrize as declarative really differs from FP, especially with lazy

In their definition of programming languages types, I'm not sure I see how SQL which they cateogrize as declarative really differs from FP, especially with lazy evaluation. Both are a succession of functions applied onto a previously declared variable : just think of a long SQL query with many ctes modifying the previous ones; each of them can be thought of as a variable which takes its value from the application of a function on other variable (a bit like the let function in ocaml). I always thought of LaTeX as being the prime example of declarative programming.