cse102day32

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Transcript cse102day32

The JOIN operation
•
Algorithm from the text
1. Construct the product table.
2. Select those rows with matching values.
3. Project to eliminate duplicate columns.
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Finish the product table
Fill in the natural join table.
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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?
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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
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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
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