| Date | November 2017 | Marks available | 2 | Reference code | 17N.2.SL.TZ0.1 |
| Level | SL | Paper | 2 | Time zone | no time zone |
| Command term | Identify | Question number | 1 | Adapted from | N/A |
Question
Define the term database transaction.
Explain the importance of durability in a database transaction.
Identify two different types of relationships within databases.
Describe the nature of the data dictionary.
Identify four responsibilities of a database administrator.
Markscheme
Award marks as follow up to [2 max].
Award [1] for:
a unit of work/logical action;
performed on a database;
independent of other transactions;
changes state of the database;
Example answer 1
A database transaction is a logical unit that is independently executed;
For data retrieval or updates;
Example answer 2
A database transaction is a unit of work;
That is either executed in full or not executed at all;
Example answer 3
A database transaction is a way of representing a state change;
And has four properties, known as ACID;
Example answer 4
A database transaction usually means a sequence of steps, treated as a unit;
For the purposes of satisfying a client’s request;
Example answer 5
A database transaction is a process carried out on a database;
Which may change its state, for example: moving money between bank accounts;
Award up to [2 max].
Example answer 1
Durability is important because transaction data changes must be available;
Even in the event of database failure;
Example answer 2
Durability means that if the system says the transaction has been committed;
The client does not need to worry about it because transactions that have been committed will survive permanently;
Example answer 3
Durability in databases is an important property because it ensures transactions are saved permanently;
And do not accidentally disappear or get erased;
Award up to [2 max].
One to one;
One to many;
Many to one;
Many to many;
Award [1] for stating what a data dictionary is and up to [3 max] for describing its contents.
It is a set of tables/a database that provides information/meta-data about the database;
A data dictionary contains
The definitions of records/entities in the database;
How much space has been allocated for and is currently used;
Default values for columns/attributes;
Integrity constraint information;
Names of (database) users, their privileges and roles;
Auditing information such as who has accessed or updated data records;
etc. (any other general database information);
They do not contain any actual data from the database, it contains only information for managing it (without a data dictionary a DBMS cannot access data from the database);
Data dictionaries are usually hidden from users to prevent them from (accidentally) deleting/changing/destroying its contents;
Award up to [4 max].
To direct and perform all activities related to a database system;
Installing and configuring software;
Creating new databases;
Designing the database schema and creating any necessary database objects;
Ensure database security is implemented to safeguard the data;
Back up and recover the database;
Work closely with application developers and system administrators to ensure all database needs are being met;
Apply patches or upgrades to the database as needed;
Training employees who use the database;
