31. Define tuple and attribute
• Attributes: column headers
• Tuple: Row
32. Define the term relation.
Relation is a subset of a Cartesian product of list domains.
33. Define tuple variable
Tuple variable is a variable whose domain is the set of all tuples.
34. Define the term Domain.
For each attribute there is a set of permitted values called the domain of that attribute.
35. What is a candidate key?
Minimal super keys are called candidate keys.
36. What is a primary key?
Primary key is chosen by the database designer as the principal means of identifying an entity in the entity set.
37. What is a super key?
A super key is a set of one or more attributes that collectively allows us to identify uniquely an entity in the entity set.
38. Define-relational algebra.
The relational algebra is a procedural query language. It consists of a set of operations that take one or two relation as input and produce a new relation as output.
39. What is a SELECT operation?
The select operation selects tuples that satisfy a given predicate. We use the lowercase letter to denote selection.
40. What is a PROJECT operation?
The project operation is a unary operation that returns its argument relation with certain attributes left out. Projection is denoted by pie (p).
• Attributes: column headers
• Tuple: Row
32. Define the term relation.
Relation is a subset of a Cartesian product of list domains.
33. Define tuple variable
Tuple variable is a variable whose domain is the set of all tuples.
34. Define the term Domain.
For each attribute there is a set of permitted values called the domain of that attribute.
35. What is a candidate key?
Minimal super keys are called candidate keys.
36. What is a primary key?
Primary key is chosen by the database designer as the principal means of identifying an entity in the entity set.
37. What is a super key?
A super key is a set of one or more attributes that collectively allows us to identify uniquely an entity in the entity set.
38. Define-relational algebra.
The relational algebra is a procedural query language. It consists of a set of operations that take one or two relation as input and produce a new relation as output.
39. What is a SELECT operation?
The select operation selects tuples that satisfy a given predicate. We use the lowercase letter to denote selection.
40. What is a PROJECT operation?
The project operation is a unary operation that returns its argument relation with certain attributes left out. Projection is denoted by pie (p).
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