In a relational data model, which one of the following statements is TRUE?
Consider a simple undirected graph of 10 vertices. If the graph is disconnected, then the maximum number of edges it can have is ____________.
Consider a relation R(A, B, C, D, E) with the following three functionaldependencies. 𝐴𝐵 𝐶; 𝐵𝐶 𝐷; 𝐶 𝐸; The number of superkeys in the relation R is _____________.
Let Ri(z) and Wi(z)denote read and write operations on a data element z by a transaction Ti, respectively. Consider the schedule S with four transactions. S: R4(x) R2(x) R3(x) R1(y) W1(y) W2(x) W3(y) R4(y) Which one of the following serial schedules is conflict equivalent to S?
Consider a relational database containing the following schemas. The primary key of each table is indicated by underlining the constituent fields. SELECT s.sno, s.snameFROM Suppliers s, Catalogue cWHERE s.sno=c.sno AND cost (SELECT AVG (cost) FROM Catalogue WHERE pno = 'P4' GROUP BY pno); The number of rows returned by the above SQL query is
Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram?
Consider a database implemented using B+ tree for file indexing and installed on a disk drive with block size of 4 KB. The size of search key is 12 bytes and the size of tree/disk pointer is 8 bytes. Assume that the database has one million records. Also assume that no node of the B+ tree and no records are present initially in main memory. Consider that each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is _______.