The JOIN operation

1
The JOIN operation

• Algorithm from the text
• Construct the product table.
• Select those rows with matching values.
• Project to eliminate duplicate columns.
• Finish the product table
• Fill in the natural join table.

2
Multiple Table Queries in SQL

• How is a multiple table query represented in SQL?
• Make a query is Design View to generate sample
  SQL
• Which role did Morgan Freeman play in the movie
  The Shawshank Redemption
• Which tables do you need to answer the question?

3
Why look at SQL?

• All queries are expressible in SQL
• Not all queries can be expressed in Design View
• Representation just as web pages are all
  composed of HTML, queries are composed of SQL
• To construct dynamic Web pages that retrieve and
  write information to a database we need SQL

4
Modifying SQL queries

• Change the SQL to find the answer to each of
  these questions
• What role did Tim Robbins play in the same movie?
• Run the query
• What role did Eddie Murphy play in Coming to
  America?
• Run the query
• Which movies have Dracula as a role?
• Run the query