What is the difference between a character field that contains a null value and a character field that contains a single blank space?

QUESTION: What is the difference between a character field that contains a null value and a character field that contains a single blank space?   [signinlocker] SOLUTION   A character field that contains a null value is zero characters long, while a...

Why does the relation created as result of a Projection operation on a relation that includes the primary key not contain fewer tuples than those in the source relation?

QUESTION: Why does the relation create a result of a Projection operation on a relation that includes the primary key not contain fewer tuples than those in the source relation?   [signinlocker] SOLUTION   There are no duplicate tuples to eliminate since the...

With which of the four types of constraints in Exercise 4 is a requirement that an attribute not contain a null value associated?

QUESTION: With which of the four types of constraints in Exercise 4 is a requirement that an attribute not contain a null value associated?   [signinlocker] SOLUTION   A not null constraint is associated with a CHECK clause....

What is the difference between a column-level constraint and a row-level constraint?

QUESTION: What is the difference between a column-level constraint and a row-level constraint?   [signinlocker] SOLUTION   A column-level constraint is imposed on a single column in the table while a row-level constraint is imposed on a set of columns in the...

What are the minimum elements that must be included in the CREATE TABLE statement in defining the structure of a table?

QUESTION: What are the minimum elements that must be included in the CREATE TABLE statement in defining the structure of a table?   [signinlocker] SOLUTION   The CREATE TABLE statement must contain the table name, the names of the columns in the table, and...

What are the undesirable functional dependencies in the relation instance of the STUCLASS relation schema shown in Exercise 6?

QUESTION: What are the undesirable functional dependencies in the relation instance of the STUCLASS relation schema shown in Exercise 6?   [signinlocker] SOLUTION   Snum → Sname, Snum → Major, Cname → Time, Cname → Room, Time → Cname, Time → Room....