Q&A Hero

Humanities

Q: Normalization is an advantage for a read-only database.
Q: Design guidelines and priorities are the same whether you're working with an updatable database or a read-only database.
Q: Read-only databases are often updated.
Q: Creating a read-only database is a job often given to beginning database professionals.
Q: To eliminate multivalued dependencies, normalize your tables so that they are all in BCNF.
Q: Writing SQL subqueries and joins against normalized tables is simple compared to the code that must be written to handle anomalies from multivalued dependencies.
Q: Multivalued dependencies create anomalies so serious that multivalued dependencies must always be eliminated.
Q: United States ZIP codes are a classic example of unneeded normalization.
Q: SQL statements that can be used to create referential integrity statements for normalized tables are created during the normalization process.
Q: The SQL DELETE TABLE statement can be used to remove unneeded tables after the normalized tables are created and populated.
Q: The SQL INSERT statement can be used to populate normalized tables.
Q: A defining requirement for BCNF is that every determinant must be a candidate key.
Q: Relations in BCNF have no modification anomalies in regard to functional dependencies.
Q: Relations are sometimes left unnormalized to improve performance.
Q: Normalization requires applications to use more complex SQL since they will need to write subqueries and joins to recombine data stored in separate relations.
Q: The presence of one or more foreign keys in a relation means that we cannot eliminate duplicated data in that table.
Q: Normalization eliminates modification anomalies and data duplication.
Q: Database design varies depending on whether you're building an updatable database or a read-only database.
Q: The elimination of modification anomalies and the reduction of duplicated data are advantages of normalization.
Q: The third step in assessing table structure is to check the validity of presumed referential integrity constraints.
Q: When examining data values as a part of assessing table structure, there is no need to try to determine foreign keys.
Q: When examining data values as a part of assessing table structure, there is no need to try to determine candidate keys other than the table's primary key.
Q: When examining data values as a part of assessing table structure, you should try to determine the table's primary key.
Q: When examining data values as a part of assessing table structure, you should try to determine multivalued dependencies.
Q: When examining data values as a part of assessing table structure, you should try to determine functional dependencies.
Q: The second step in assessing table structure is to examine data values and determine dependencies and keys.
Q: When examining data values as a part of assessing table structure, you should try to determine three types of keys: the primary key, any candidate keys, and any foreign keys.
Q: When examining data values as a part of assessing table structure, you should try to determine two types of dependencies: functional dependencies and multivalued dependencies.
Q: To limit the number of rows retrieved from a table, use the SQL TOP keyword.
Q: To determine the number and type of columns in a table, use the SQL construct COUNT(*).
Q: To count the number of rows in a table, use the SQL construct COUNT(ROWS).
Q: The first step in assessing table structure is to count rows and examine columns.
Q: When you are given a set of tables and asked to create a database to store their data, the first step is to assess the tables' structure and content.
Q: Every time we break up a relation during the normalization process, we may have to create a referential integrity constraint.
Q: A defining requirement for Boyce-Codd Normal Form (BCNF) is that every candidate key must be a determinant.
Q: A relation is in Boyce-Codd Normal Form (BCNF) if and only if it is in 3NF and every determinant is a candidate key.
Q: Candidate keys are called interlocking candidate keys when they share one or more attributes.
Q: An attribute is considered to be a non-key attribute when it is a non-prime attribute, which means that the attribute is not contained in any candidate key.
Q: The condition that a non-key attribute determines another non-key attribute is known as transitive dependency.
Q: A relation is in 3NF if and only if it is in 2NF and there are no non-key attributes determined by another non-key attribute.
Q: A relation is in 2NF if and only if it is in 1NF and all non-key attributes are determined by the entire primary key.
Q: Any table that meets the definition of a relation is in 2NF.
Q: Any table that meets the definition of a relation is said to be in first normal form (1NF).
Q: Relations are classified into normal forms based on the types of modification anomalies that they are vulnerable to.
Q: A deletion anomaly exists when deleting data about one entity results in the loss of data about another entity.
Q: Undesirable consequences of changing the data in a relation are called modification anomalies.
Q: If a table meets the minimum definition of a relation, it has an effective or appropriate structure.
Q: A referential integrity constraint limits the values of a foreign key.
Q: A constraint that requires an instance of an entity to exist in one relation before it can be referenced in another relation is called an insertion anomaly.
Q: A referential integrity constraint is used to make sure the values of a foreign key match a valid value of a primary key.
Q: A foreign key is one or more columns in one relation that also is the primary key in another table.
Q: Surrogate keys are normally not shown on forms or reports.
Q: Surrogate keys usually slow performance.
Q: A surrogate key is an artificial column that is added to a relation to be its primary key.
Q: A primary key is a candidate key that has been selected to uniquely identify rows in a relation.
Q: A relation can have only one candidate key.
Q: A candidate key is one of a group of keys that may serve as the primary key in a relation.
Q: It is possible to have a relation that does not have a key.
Q: A key can be composed of a group of attributes taken together.
Q: A combination key is a group of attributes that uniquely identifies a row.
Q: A row can be uniquely identified by a key.
Q: A key is a combination of one or more columns that is used to identify particular rows in a relation.
Q: A determinant of a functional dependency may or may not be unique in a relation.
Q: Given the functional dependency A → B, then it is necessarily true that B → A.
Q: Given the functional dependency (A, B) → C, then it is true that A → C and B → C.
Q: Given the functional dependency A → (B, C), then it is true that A → B and A → C.
Q: Given the functional dependency (A, B) → C, the attributes (A, B) are referred to as a composite determinant.
Q: Functional dependencies can involve groups of attributes.
Q: In the functional dependency shown as A → B, B is the determinant.
Q: The functional dependency noted as A → B means that the value of A can be determined from the value of B.
Q: Attribute Y is functionally dependent on attribute X if the value of attribute X determines the value of Y.
Q: In functional dependencies, the attribute whose value is known or given is referred to as the determinant.
Q: If by knowing the value of A we can find the value of B, then we would say that B is functionally dependent on A.
Q: A functional dependency is a relationship between attributes such that if we know the value of one attribute, we can determine the value of the other attribute.
Q: A tuple is a group of one or more columns that uniquely identifies a row.
Q: The columns of a relation are sometimes called tuples.
Q: In relational terms as defined by E.F. Codd, a column is called an attribute.
Q: In relational terms as defined by E.F. Codd, a row is called a tuple.
Q: A relation is a table composed of columns and rows.
Q: A characteristic of a relation is that the rows of a relation may hold identical values.
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