Internet Fundamentals/Databases

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Entity Relationship Diagram
OpenOffice Base
SQL

This lesson introduces database concepts.

Objectives and Skills[edit]

Objectives and skills for this lesson include:[1][2]

  • Recognize essential database concepts.

Readings[edit]

  1. Wikipedia: Database
  2. Wikipedia: Relational database
  3. Wikipedia: SQL

Multimedia[edit]

  1. YouTube: Relational Database Concepts
  2. YouTube: Intro to SQL
  3. YouTube: SQL JOIN Statement
  4. YouTube: SQL GROUP BY, HAVING & ORDER BY
  5. YouTube: SQL INSERT, UPDATE, and DELETE

Activities[edit]

  1. Complete one or more of the following tutorials:
  2. Practice writing single-table SELECT queries using W3Schools SQL TryIt Editor.
    • Select all customers (SELECT *).
    • Select only customer id and customer name fields (SELECT fields).
    • Select customer name, address, city, and postal code for all customers from the United Kingdom (WHERE field = 'value').
    • Select contact name and customer name for all customers, sorted alphabetically by contact name (ORDER BY field).
    • Count the total number customers (COUNT(*)).
    • Count the number of customers from each country (GROUP BY).
    • Count the number of customers from each country and sort the list in descending order by count and ascending order by country in case of a tie (GROUP BY, ORDER BY).
    • Count the number of customers from each country and sort the list in descending order by count and ascending order by country in case of a tie, listing only those countries with more than 10 customers (GROUP BY, ORDER BY, HAVING).
  3. Practice writing multiple-table SELECT queries using W3Schools SQL TryIt Editor.
    • Select customer name, order ID, and order date for all customers (INNER JOIN).
    • Select customer name, order number, and order date for all customers, renaming the OrderID field as Order Number (INNER JOIN, AS).
    • Select customer name, order number, and order date for all customers, sorted by customer name and order number (INNER JOIN, AS, ORDER BY).
    • Select order number, order date, product name, and quantity ordered for all customers (INNER JOIN, AS).
    • Select order number, order date, product name, quantity ordered, and extended price (quantity * price) for all customers (INNER JOIN, AS, calculated field).
    • Select order number, order date, product name, quantity ordered, and extended price for customer 2 (INNER JOIN, AS, calculated field, WHERE).
    • Select order number, order date, product name, quantity ordered, and extended price for customer 'Around the Horn' (INNER JOIN, AS, calculated field, WHERE).
  4. Practice writing INSERT, UPDATE, and DELETE queries using W3Schools SQL TryIt Editor.
    • Add a new shipper with ID 4, name 'On Time Delivery', and phone '(503) 555 0123' (INSERT).
    • Increase prices on all products by 1 (UPDATE).
    • Reduce prices on all products by 1 (UPDATE).
    • Change the new shipper's name from 'On Time Delivery' to 'On-Time Delivery' (UPDATE, WHERE).
    • Delete the new shipper (DELETE, WHERE).

Lesson Summary[edit]

  • A database is an organized collection of data.[3]
  • A relational database is a collection of schemas, tables, queries, reports, views, and other elements.[4]
  • A database-management system (DBMS) is a computer-software application that interacts with end-users, other applications, and the database itself to capture and analyze data.[5]
  • A general-purpose DBMS allows the definition, creation, querying, update, and administration of databases.[6]
  • Well-known DBMSs include MySQL, PostgreSQL, EnterpriseDB, MongoDB, MariaDB, Microsoft SQL Server, Oracle, Sybase, SAP HANA, MemSQL, SQLite and IBM DB2.[7]
  • Virtually all relational database systems use SQL (Structured Query Language) as the language for querying and maintaining the database.[8]
  • SQL (Structured Query Language) is a special-purpose programming language designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS).[9]
  • Data Manipulation Language (DML) commands include SELECT, INSERT, UPDATE, and DELETE.[10]
  • The SQL SELECT statement returns a result set of records from one or more tables.[11]
  • An asterisk ("*") can be used to specify that the query should return all columns of the queried tables.[12]
  • SQL statements are terminated with a semicolon (";").[13]
  • A WHERE clause in SQL specifies that a SQL Data Manipulation Language (DML) statement should only affect rows that meet specified criteria.[14]
  • By default, relational database systems may return data rows in any order, or more specifically, without any order.[15]
  • An ORDER BY clause in SQL specifies that a SQL SELECT statement returns a result set with the rows being sorted by the values of one or more columns.[16]
  • A SQL JOIN clause combines columns from one or more tables in a relational database.[17]
  • An SQL INSERT statement adds one or more records to any single table in a relational database.[18]
  • An SQL UPDATE statement changes the data of one or more records in a table. Either all the rows can be updated, or a subset may be chosen using a condition.[19]
  • An SQL DELETE statement removes one or more records from a table. Either all records are removed, or a subset may be chosen using a condition.[20]

Key Terms[edit]

AJAX (Asynchronous JavaScript And XML)
A set of Web development techniques using multiple Web technologies on the client side to create asynchronous Web applications that can send and retrieve data from a server asynchronously (in the background) without interfering with the display and behavior of the existing page.[21]
data modeling
A process used to define and analyze data requirements needed to support the business processes within the scope of corresponding information systems in organizations.[22]
database
An organized collection of data.[23]
database management system (DBMS)
A computer-software application that interacts with end-users, other applications, and the database itself to capture and analyze data.[24]
field
A set of data values of a particular simple type, one for each row of the table.[25]
foreign key
A field (or collection of fields) in one table that uniquely identifies a row of another table or the same table.[26]
index
A data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure.[27]
many-to-many relationship
A type of cardinality that refers to the relationship between two entities A and B in which A may contain a parent instance for which there are many children in B and vice versa.[28]
one-to-many relationship
A type of cardinality that refers to the relationship between two entities (see also entity–relationship model) A and B in which an element of A may be linked to many elements of B, but a member of B is linked to only one element of A.[29]
Open Database Connectivity (ODBC)
A standard application programming interface (API) for accessing database management systems (DBMS).[30]
primary key
A field (or collection of fields) in one table that uniquely identifies a row in the table.[31]
query
A precise request for information retrieval with database and information systems.[32]
record
A single, implicitly structured data item in a table.[33]
relational database
A collection of schemas, tables, queries, reports, views, and other elements.[34]
Structured Query Language (SQL)
A domain-specific language used in programming and designed for managing data held in a relational database management system[35]
table
A collection of related data held in a structured format within a database, consisting of columns and rows.[36]

Assessments[edit]

See Also[edit]

References[edit]