Quantification in sql, PL-SQL Programming

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.
Posted Date: 1/18/2013 4:20:07 AM | Location : United States







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