Systems Analysis and Database Design: Quiz 3

Systems Analysis and Database Design: Quiz 3
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Question Two
A compound key in the database is used to uniquely identify data occurrence with more
than one attribute or columns. Ideally, composite keys are used when there are non-composite
candidate keys. The use of composite keys is dependent on the personal need of any database
developer. It can be used when the developer wants the primary key in a given table has to
achieve a predefined purpose (Asha, Kumar & Kumar 2014, pp. 2232). With the use of
compound keys, it has been possible to normalize data which cannot be achieved with just a
single primary key entity attribute. Finally, DDL is used to strengthen referential integrity to the
data. In cases where data tables have many records, use of single entity in the database does not
guarantee strong entity keys.
Question Six
Data Definition Language (DDL) is a computer and database based language which is
used by database administrators to interact and modify database objects. In this case, database
objects can be table views, indexes, and schemas. In Structured Query Language (SQL), some of
the commonly used DDL’s are create, drop and alter commands (Meijer & Bierman 2011, pp.
30). Through the use of DDL, it has been possible to interact and manipulate database through
the use of Data Manipulation Language (DML). Important to note is that without DDL, it is not
possible to have DML. Therefore, DDL server as the basis of all database operations and
manipulations such as DML and TCL.
Question Seven
The distinct keyword is used in conjunction with other data manipulation language such
as select. The distinct keyword is used in the structured query language (SQL) to eliminate