Today we introduce complex operations like Joins.

Time estimation: 3 hours

Learning Objectives
- Define aggregation and give examples of its use.
- Write queries that compute aggregated values.
- Trace the execution of a query that performs aggregation.
- Explain how missing data is handled during aggregation.
- Explain the operation of a query that joins two tables.
- Explain how to restrict the output of a query containing a join to only include meaningful combinations of values.
- Write queries that join tables on equal keys.
- Explain what primary and foreign keys are, and why they are useful.
- Explain what an atomic value is.
- Distinguish between atomic and non-atomic values.
- Explain why every value in a database should be atomic.
- Explain what a primary key is and why every record should have one.
- Identify primary keys in database tables.
- Explain why database entries should not contain redundant information.
- Identify redundant information in databases.
- Write statements that create tables.
- Write statements to insert, modify, and delete records.
- Write short programs that execute SQL queries.
- Trace the execution of a program that contains an SQL query.
- Explain why most database applications are written in a general-purpose language rather than in SQL.