CS6400 Exam 3 Questions Answered Correctly Latest Update (Graded A+)

CS6400 Exam 3 Questions Answered Correctly Latest Update (Graded A+) Natural Join - Answers The result of this is the set of all combinations of tuples in R and S that are equal on their common attribute names. A special case of an equijoin. Left Outer Join - Answers A construct operator which results in the set of all combinations of tuples in R and S that are equal on their common attribute names, in addition (loosely speaking) to tuples in R that have no matching tuples in S. Insert - Answers A basic SQL operation in which new records are added to a table. Delete - Answers A basic SQL operation in which existing records are removed from a table. Update - Answers A basic SQL operation in which existing records are changed in a table. Select * - Answers A basic SQL operation in which existing records are chosen from a table. Select Distinct - Answers A basic SQL operation in which only unique existing records are chosen from a table. Intersect - Answers Set operator which includes all tuples that are in both R and S. Union - Answers Set operator which includes all tuples that are either in R or in S or in both R and S. Duplicates are removed. Union All - Answers set operator which includes all tuples that are either in R or in S or in both R and S. Duplicates are not removed. Count(*) - Answers SQL function which returns the number of rows that matches the specified criteria. Group By - Answers SQL operator which rolls up the result set by one or more columns. Equijoin - Answers A theta join using the equality operator Difference / Minus - Answers Set operator which includes all tuples that are in R but not in S Theta Join - Answers A construct operator which allows for arbitrary comparison relationships (such as >=) Inner Join - Answers Requires each row in the two joined tables to have matching column values. Cartesian Product - Answers A construct operator which results in the set of all combinations of tuples in R and S Reflexive Inference Rule - Answers If Y is a subset of X, then X -> Y. i.e. EG -> G Augmentation Inference Rule - Answers If X -> Y, then XZ -> YZ for any Z i.e. E->A, therefore EG->AG Transitive Inference Rule - Answers If X -> Y and Y -> Z, then X -> Z, i.e. B->E, E->A, therefore B->A Decomposition Inference Rule - Answers If X -> YZ then X -> Y and X -> Z Composition Inference Rule - Answers If X -> Y and A -> B then XA->YB Union Inference Rule - Answers If X -> Y and X-> Z then X -> YZ Pseudo Transitivity Inference Rule - Answers If X -> Y and YZ -> W then XZ -> W 1NF - Answers If and only if the domain of each attribute contains only atomic (indivisible) values, and the value of each attribute contains only a single value from that domain. May have redundancy. 2NF - Answers The table is in 1NF and all the columns depend on the tables' primary key (transitively or not) 3NF - Answers The table is in 2NF and all of its columns not transitively dependent on the primary key Lossless Join Decomposition - Answers A concept in which the following are true: Union of Attributes of R1 and R2 must be equal to attribute of R, the Intersection of Attributes of R1 and R2 must not be NULL, and the Common attribute must be a key for at least one relation Relational Tuple Calculus (with some Algebra operators) - Answers What SQL is mathematically based upon NFNF (NF^2) - Answers A data structure that is not a relation at all First Rule of Normalization - Answers No redundancy of facts Second Rule of Normalization - Answers No cluttering of facts Third Rule of Normalization - Answers Must preserve information Fourth Rule of Normalization - Answers Must preserve functional dependencies Information Loss - Answers When, after decomposition, we get more (or less) information than was initially present in the base dataset. Dependency Loss - Answers When we cannot enforce the functional dependencies Functional Dependence - Answers A relationship that exists when one attribute uniquely determines another attribute. BCNF - Answers A normal form in which every determinant is a candidate key Determinant - Answers A set of attributes on which some other attribute is fully functionally dependent Full functional dependence - Answers A state of database normalization that equates to the normalization standard of Second Normal Form (2NF) Normalization Mnemonic - Answers All attributes must depend on the key, the whole key, and nothing but the key, so help me Codd Closure - Answers Given a set F of functional dependencies, the set of all functional dependencies logically implied by F Hard Disk - Answers A non-volatile storage device where the bulk of the data and applications are stored. Characterized by low cost, relatively slow access speed (latency between 2-10 ms) and large size (typically in the TB) Main Memory - Answers A volatile storage device which stores frequently used program instructions to increase the general speed of a system. Characterized by high cost, relatively small amount of storage but fast access speed (latency between 15-90 ns) and small size (typically in the GB) Cache - Answers A volatile storage device which typically sits on the CPU. Characterized by very small amount of storage but very fast access speed (latency typically 4-5 CPU cycles) and very small size (typically 32 KB for L1, 256 KB for L2) Bus - Answers Transports data from the disk to main memory (and then back) Platter - Answers The circular disk on which magnetic data is stored in a hard disk drive Sector - Answers The smallest physical unit that could be transported from the disk to main memory Track - Answers The thin concentric circular strips of sectors Cylinder - Answers A division of data in a disk drive, concept is concentric, hollow, cylindrical slices through the platters, collecting the respective circular tracks aligned through the stack of platters. Head - Answers A device that reads and writes data in a hard drive by manipulating the magnetic medium that composes the surface of an associated disk platter. Block - Answers The standard physical part of the disk that is transferred - a sector or group of sectors Unspanned representation - Answers To make sure a record fits on a block; if this means there