Quiz 1 Flashcards
(25 cards)
Keeping records of data is [only] possible with relational databases. (T/F)
F
Instead of databases, if file-based systems are used, then the application program is MORE tightly coupled to the file formats. (T/F)
T
A program using a plain text file to store its data will NEVER have to be changed if the file, which originally used a ‘,’ to separate values on one line, suddenly changes to using ‘|’ as a separator character. (T/F)
F
DBMSs provide a standard interface that allows users to query database data in the same manner, irrespective of the actual database package vendor. (T/F)
T
Transaction Processing Systems must be highly available (i.e.,have low down-time), but as they are not real-time systems, response time to the user is not a concern in such systems. (T/F)
F
In a database table cell, you can store multiple values. For example, if you store the id of the owner of a bank account in a database table cell, and an additional owner is added, you can just [add] the id of the second owner to the data already in the table cell. (T/F)
F
Each combination of data items that may be used to uniquely identify a row in a database table is called a [candidate key]. (T/F)
T
Setting up a [One-Many] relationship in a database [always] requires the creation of a new table in the database to represent the relationship. (T/F)
F
While designing the conceptual schema of a database, it is important to keep in mind the the same data [related to the same object] (e.g., the same student) should not be replicated in two different database tables. (T/F)
T
By establishing the integrity constraint among two tables in a database, we also set up a relationship between the real-world entities corresponding to those tables that must be shown in an (UML style) database structure (E-R) diagram. (T/F)
T
Which of the following is not a key element of (UML style) data models? i. Indentifiers (i.e., names of entities (tables) and relationships) ii. Tables (or entities) iii. Objects (i.e., actual instances of entities and relationships) iv. Table attributes (i.e., column names) v. Relationships
iii. Objects (i.e., actual instances of entities and relationships)
One of the candidate keys of a table could be chosen as _______ of the table. i. Foreign key ii. Primary key iii. Referential Integrity constraint iv. Constraint v. Index
ii. Primary key
If deleting a record (row) from a table cuases a related record (row) in another table to automatically get deleted, then the entities in the second table are said to be _________ entities. i. Subclass ii. Weak iii. Recursive iv. Redundant v. Multi-valued
ii. Weak
+++++++++ +++++++++++
+ ORDER ++++++++++++++++++++ CUSTOMER +
+++++++++ +++++++++++
If a given customer place many orders and given order can be placed by at most one costumer, then the relationship betwwen thse two entities is one-many. Every customer must have at least one order, otherwise the customer will not be in the database. What should be placed on the ORDER and CUSTOMER sides of the relationship line shown above.
i. 1 on ORDER, 1..* on CUSTOMER
ii. 1 on ORDER, 1 on CUTOMER
iii. 1..* on ORDER, 1 on CUSTOMER
iv. 1..* on ORDER, 1..* on CUSTOMER
v. 0…* on ORDER, 1 on CUSOMER
iii. 1..* on ORDER, 1 on CUSTOMER
If a [foreign key column in Table B is linked to the [primary key] column of Table A, and if we set up a constraint betwwen these two that includes the words “ON DELETE NO ACTION”, then which of the following is true?
i. If an entity from Table A is deleted, then the foreign key values in Table B that link to the deleted primary key in Table A will be set to NULL.
ii. If an entity from Table A willis deleted, them both the foreign key values in Table B and the related primary key values in Table A will be set to NULL.
iii. If an entity from a TABLE A is deleted, then if there are linked entities in Table, not deletes will take place.
iv. If an entity from a TABLE B is deleted, an there are linked entitites in Table A, no deletes will take place.
v. Entitied in either table can [never] be deleted.
iii. If an entity from a TABLE A is deleted, then if there are linked entities in Table, not deletes will take place.
If customers of the VISA credit card system are not to be frustrated because theu cannot use their credit card in countries other than the country of issue, then VISA’s trnasacction processing system must be designed and implemented to be __________.
Responsive and highly available
When considering a relationshipo in the (UML style) data model diagram, it is important to identify its _______ , becuase this can affect the way in which this relationship is mapped to tables in the database schema.
Multiplicity
The term used to define the set tables in database, the columns in each table , primary key and the types of data in columns is “ _______ schema” (as opposed to physical schema, which refers to the data structures used by the vendor in their implementation).
Conceptual
Making a primary key from one table in the database into a foreign key in another database results in setting up a _______ constraint between these tables.
feternal integrity
A(n) ________ put in a column in a particular row of a database table indicates that either the data table for that column is undefinred for the instance implied by that row, or that the data for that column is as yet unavailable for that column of that row.
null value
A(n) ________ is a group of one or more attributes that uniquely identifies a row.
candidate key
For some relations, you can run into unexpected problems when you delete the data - e.g., you might lose data you did not want to lose. This problems in known as ___________ .
delete anomalies
Many times we break up a relation during the normaliation process (such as we break one relegation into two as we did in class with the relation showing Student’s ID, Activity he/she signed up for and Fee for that activity), we may create _________ constraints amogst (say) a pair of columns in the two new tables.
integrity
Normal forms are nested - this means that if a relation is in 2NF, it is also in _________.
First normal form.
