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Questions and Answers
What is the smallest unit of data storage?
Which data processing method involves using a keyboard and typewriter?
What is a 'Byte' in terms of data?
What is the main purpose of SQL (Structured Query Language)?
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What does the term 'Batch processing' refer to?
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What is a Nibble in terms of data?
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What is a Field in a table?
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Which SQL clause is used to filter records based on a specified condition?
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What does the term 'Projection' refer to in SQL?
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In a relational database, what is the purpose of the 'null' value in a field?
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What is the role of Authentication in databases?
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What is the purpose of an Arithmetic Expression in databases?
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Study Notes
Data Storage Units
- BIT: the smallest unit of data storage
- Nibble: a 4-bit unit of data, half of a byte
- Byte: a unit of data equivalent to eight binary digits
Data Processing Cycle
- Gathering information: origin and input
- Data processing: encoding, input, processing, and output
- Storing: saving or not storing the output
Data Accessing Methods
- Manual Method: using pen and paper
- Mechanical Method: using keyboard and typewriter
- Electronic Method: data processing 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
Data Validation
- Checking for errors to minimize erroneous data
- Data must conform to specific criteria before being processed
Database Concepts
- SQL: Structured Query Language used to query all databases
- RDBMS: Relational Database Management System that uses the concept of linking different tables
Database Components
- Table: a collection of related data entries with rows and columns
- Field: a column in a table 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
Database Security
- Controlling Database Access: an important aspect of database security
- DY: denies user action on the objects within the database
- User: an account that can connect and access objects inside the database
- Enema: a group of database objects such as tables, views, clusters, and packages
SQL Select Statement
- Projection: selecting a certain column or field from a table
- Selection: retrieving a subset of rows or records in a table
- Joining: combining data from more columns or tables
- Generating Report: using the SELECT statement to retrieve data from the database
SQL Statement Options
- SELECT * FROM Tablename: retrieves all columns from a table
- SELECT column1, column2, ... FROM tablename: retrieves specific columns from a table
- ORDER BY: arranges data in either ascending or descending order
- WHERE: represents the command that will create a condition to be satisfied
- Arithmetic Expression: used to perform calculations
- Unary Operator: operates on one operand, denoting positive or negative values
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Description
Test your knowledge on the various capabilities of the SQL SELECT statement. This quiz covers topics such as data representation, database organization, storage units, and data processing.
