Quantification in SQL

To quantify something, as the theory book has it, is to state its quantity, to say how many of it there are. For example, in Tutorial D the expression COUNT(r) denotes the number of tuples in the relation r, to be interpreted as the number of objects represented by those tuples that satisfy a predicate that r is considered to represent. Universal quantification-stating that something is true of all objects under consideration-is involved in expressions such as

1. AND(r,c), meaning that all objects that satisfy a predicate for r also satisfy the condition (another predicate) c, and
2. IS_EMPTY(r), meaning that no object satisfies a predicate for r-in other words, every object satisfies the negation of that predicate.