1. What is sql?

2. Databases
In the past, databases mostly held boring stuff: census data, employee records, bank accounts, …
Today, databases hold virtually all of humankind’s collected information
Everything you’ve ever read, seen (or done according to Snowden)
Everything on the web (cat pictures)
Scientific data (mostly LHC stuff)
Medical data and so on
Corny art from:

3. Databases are interesting
Databases use restricted programming languages
One of the few places where non-Turing-complete languages are an advantage
This leads to very terse programming and deep query-optimization problems
Concurrency and Transactions are essential
Many activities happen simultaneously
Need to heavily utilize parallel programming techniques

4. What is the advantage to SQL not being Turing-Complete?
Easier to optimize
Easier to write
Lies! SQL is Turing-complete
I don't know what Turing-complete is

5. Data Models - Components
Mathematical representation of the data
Relational Models (CSV) = tables
Semi-structured Models (XML, JSON) = trees/graphs
Operations on data (what is allowed, i.e. comparisons, equality, math)
Constraints (what types of data are allowed, and where)

6. Attributes (column headers)
Relations are tables
Attributes (column headers)
name
FavoriteShow
Ian
Stargate SG1
Cam
True Detective
Caleb
GLTAS maybe
Tuples (rows)
Relation name
shows

7. Schemas (sound familiar?)
Relation schema = relation name and attribute list
Optionally: types of attributes
Example: shows (name, FavoriteShow) or shows (name TEXT, FavoriteShow TEXT)
Database = collection of relations
Database schema = set of all relation schemas in the database

8. Why Relations? Very simple model
Often (but not always) matches how we think about data
Abstract model that underlies SQL, the most important database language today

9. Database Schemas in SQL
SQL is primarily a query language, for getting information from a database.
But SQL also includes a data-definition component for describing database schemas.

10. What is the difference between: Record, tuple, and row
Nothing (in the context of this class)
The way they are spelled
How insulting they are
Whether the order of the elements matter