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This guide explores essential software issues focusing on readability, font styles, and database concepts. Learn how to measure readability through words per sentence and syllables per word, along with tips for writing in plain English. We delve into font types, distinguishing between serif and sans serif, and their characteristics. The database section covers fundamental concepts such as relationships between tables, designing tables, and structuring queries effectively. Gain insights into managing data relationships like one-to-one, one-to-many, and many-to-many, ensuring your database is efficient and functional.
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CS 101 – Nov. 9 Text software issues (continued) • Readability • Fonts • Database concepts • Relationships • Queries
Readability • First, need to measure: • Words per sentence • Syllables per word • How to Write Plain English by Flesch: 206.835 – 84.6*spw– 1.015*wps 90’s = fifth grade 30’s = college level
Fonts • Font = style of printing • Typeface • Point size • Ex. Times 10, Helvetica 12 • Fonts can be distinguished by • Sarif or sans sarif • Proportional or non-proportional
Font types • Sarif = has feet • Sans sarif = no feet • Look at: i, h, n, r, … (but not t!) • Proportional = width of characters changes • Non-proportional = all have same width
Access review • Purpose: Manage data • Parts of a database • If your database has only 1 table, you are better off using Excel • Relationship between tables? • None • One-to-one • One-to-many (most common) • Many-to-many
Table design • What fields to we need? • Age? store birth date • GPA? store credits and quality points • What year? store date of admission • Store data in its smallest parts (e.g. address) • Calculated fields don’t belong in table!
Queries • Usually we ask about info from 2+ tables. • By default, a query will perform an operation called a Cartesian Product, which gives all possible combinations. • Ex. Name and City tables:
Cartesian Product • Given 2 sets, find all possible ordered pairs. • Analogously for more than 2 sets. • Great example: choosing a menu. • Appetizer • Entrée • Dessert • Unfortunately, most DB queries are not like this! We get too many results.
Relationships • We want to tell Access that there is a relationship between the tables, so we can create meaningful query. • One-to-many is most common • “Each city has one or more employees.” • Now, query will return 3 results instead of 6: Miami Bob Pittsburgh Mary Ken
One-to-One • Can be useful if some information is confidential. • What if we didn’t have any relationship?
1-1 Query • When you combine tables that have a 1-1 relationship: Access will look for fields that are the same, and use this as a filter. • In previous example, we’ll have 2 results instead of 4. Employee 101’s information Employee 102’s information • Let’s look at another example.
Relationship summary • When you have 2+ tables, there is almost always a relationship • They share one field in common. • Can you tell what it is? • Ex. Customers & Orders • Ex. Publishers & books • Ex. Students & Class roster
Referential integrity Keep related records consistent Cascade delete: allow deletion of “one” Cascade update: allow update of “one” For example, changing someone’s CustomerID. One-many Relationships
Many-to-many • Ex. Customers to products • Implement as 2 one-to-one • “Order details” table • Think of possible queries based on the 5 tables given in handout.
