SQL Select Statement Capabilities Quiz

Data Basics

• Data refers to facts, absence, assumptions, or occurrences
• A database is an organized collection of information
• Data storage units on a computer include:
  • Bit: the smallest unit of data storage
  • Nibble: a 4-bit unit of data or half of a byte
  • Byte: a unit of data equivalent to eight binary digits

Data Processing Cycle

• Gathering information or data
• Data encoding and input
• Database processing and calculation
• Output and saving or storing results

Data Accessing Methods

• Manual method: using pen and paper
• Mechanical method: using keyboard and typewriter
• Electronic method: using computers

Data Processing Modes

• Batch processing: the most inexpensive and efficient method for large organizations
• On-line processing: transactions are entered directly into the computer and processed immediately

Database SQL Concepts

• RDBMS: Relational Database Management System
• Table: a collection of related data entries with rows and columns
• Field: a column in a table that is designed to maintain specific information about every record
• Record: an individual entry that exists in a table
• Column: a vertical entity in a table that contains all related data
• Null value: a value in a field with no value
• Constant: a something with a fixed value
• Variable: something that may have a varying value over time
• Operators: come as input for operators
• Expression: a well-formed string containing variables, constants, or functions

Database Security

• Controlling database access is an important matter in database management
• User: an account that can connect and access objects within the database
• Schema: a group of database objects such as tables, views, clusters, procedures, and packages
• Authentication: means verifying the identity of someone who wants to use data resources or application

Capabilities of SQL Select Statement

• Projection: selecting certain columns or fields from a table
• Selection: retrieving a subset of rows or records in a table that satisfy a condition
• Joining: combining data from more than one column or table
• Generating report: using the output of the select statement to create a report
• Basic select statement: SELECT * FROM tablename
• Using arithmetic expressions and null values
• Using the WHERE clause to specify conditions
• Using the ORDER BY clause to arrange data in ascending or descending order