Database Management-Final Exam Guaranteed Success
Relationship ️ Association between entities.
Types of relationships: ️ One-to-many: Each rep is associated with many customers. Each customer is
associated with a single rep.
Database ️ A structure that can store information about diff...
Database Management-Final Exam Guaranteed Success
Relationship ✔️ Association between entities.
Types of relationships: ✔️ One-to-many: Each rep is associated with many customers. Each customer is
associated with a single rep.
Database ✔️ A structure that can store information about different categories of information and
relationships between those categories.
Database Management System (DBMS) ✔️ A program, or collection of programs, through which users
interact with a database; can create forms and reports.
Advantages of database processing: ✔️
- Getting more information from the same amount of data
- Sharing data
- Balancing conflicting requirements
- Controlling redundancy
- Facilitating consistency
- Expanding security
- Increasing productivity
- Providing data independence
Disadvantages of database processing: ✔️
- Larger file size
- Increased complexity
- Greater impact of failure
- More difficult recovery
Rules of a Relation: ✔️ A two-dimensional table in which:
, - Entries are unnormalized.
- Each column has a distinct name (attribute name).
- All values in a column are values of the same attribute.
- Order of columns is immaterial.
- Each row is distinct.
- Order of rows is immaterial.
Attribute ✔️ Characteristic or property of an entity (field/column).
Primary Key ✔️ A column or collection of columns of a table (relation) that uniquely identifies a given
row in that table.
Foreign key ✔️ Field(s) whose value is required to match the value of the primary key for a second
table.
Relational database ✔️ A collection of relations or tables.
Basic relational algebra operations: ✔️
- SELECT - retrieves certain rows from an existing table (based on criteria) and saves them as a new table
(includes WHERE).
- PROJECT - causes only certain columns to be included in the new table (includes OVER).
- JOIN - two tables being joined.
Structure of an SQL query: ✔️ SELECT-FROM-WHERE.
Use of compound conditions in WHERE statements: ✔️ Connecting two or more simple conditions
using one or both (AND/OR).
Use of LIKE: ✔️ Include in the WHERE clause.
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