CIS Exam 2

- is some identifiable thing that users want to track:

• Customers
• Computers
• Sales

Describe an entity’s characteristics.All entity instances of a given entity class have the same attributes, but vary in the values of those attributes.

Short for Data Definition Language, DDL is a computer language that is used to define data structures. In Database Management Systems (DBMS), it is used to specify a database scheme as a set of definitions (expressed in DDL). In SQL, the Data Definition Language (DDL) allows you to create, alter, and destroy database objects.

Entity relationship model

No legal or binding force; invalid.

Recorded facts and figures

Is a plan or blueprint for a database design.

• A data model is more generalized and abstract than a database design.

It is easier to change a data model then it is to change a database design, so it is the appropriate place to work through conceptual database problems

Data Manipulation language It is used to retrieve, store, modify, delete, insert and update data in database.

• - is a candidate key selected as the primary means of identifying rows in a relation.
  • There is only one primary key per relation.
  • The primary key may be a composite key.
  • The ideal primary key is short, numeric, and never changes.

Aggregate functions perform a calculation on a set of values and return a single value. Except for COUNT, aggregate functions ignore null values. Aggregate functions are frequently used with the GROUP BY clause of the SELECT statement.
Aggregate functions can be used as expressions only in the following:

• The select list of a SELECT statement (either a subquery or an outer query).
• A HAVING clause.

- Join conditions can be specified in either the FROM or WHERE clauses

Organizes the information about a single topic into rows and columns

Entities can be associated with one another

tuple uniquely identifies a slice of data from a cube. The tuple is formed by a combination of dimension members, as long as there are no two or more members that belong to the same hierarchy.

- are attributes whose values are generated from other attributes---Something u can calculate from other attributes