Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [tuple-relational-calculus]

0
votes
1answer
20 views

Whether same output is obtained for the two queries

Consider the following SQL Queries executed on the relation Employee: Employee (Eid, Ename, sal) Eid is the primary key Queries: S1:SELECT count (*) FROM Employee; S2: SELECT count (Eid)...
-1
votes
2answers
52 views

Is it possible to do a NULL comparison in Relational Algebra?

Please consider the following question given in a booklet: I have read about databases from Database System Concepts - by Henry F. Korth, but never saw an instance where we could do a NULL comparison ...
1
vote
1answer
62 views

Relational calculus to SQL

I am somewhat aware of the correspondence between (tuple and domain) relational calculus, relational algebra, and SQL. To the best of my understanding, one should be able to automatically convert a ...
0
votes
0answers
28 views

Relational calculus expression for projection (Database Management)

I recently came across this question: Let the following relation schemas be given: $R=(A,B,C)$ $S=(D,E,F)$ Let relations r(R) and s(S) be given. Give an expression in the tuple relational calculus ...
0
votes
1answer
83 views

Use of existential quantifier in tuple relational calculus

It is somewhat confusing to me when to use quantifiers in tuple relational calculus (TRC). I stumbled upon following problem and I am still scratching my head thinking why not TRC query can be ...