Relational Math. Relational Algebra. The rules for combining one or more numbers (or symbols standing in for numbers) to obtain another number is called algebra .
Customer.* refers to all of the columns.
The condition (predicate) selecting out particular rows.
ANDed conditions are entered on the same line.
ORed conditions are entered on separate lines.
Choose columns and check to show them.
Columns that will appear.
Step 1 would be to create union-compatible tables using projection. Step 2 would be to take the union of these tables.
Dragging a field icon from one table to another establishes a relationship. Right click on a line to remove a relationship from the query.
SQL has an INTERSECT operation like its UNION operation, but it is not supported by Access.
Uses concatenation and a subquery.
Note: Access adds lots of parentheses.
Ernest Borgnine and James Brown removed.
Same as the second version of the Intersection query except IN NOT IN
Cardinality(AB) = Cardinality(A) * Cardinality(B)
Degree(AB) = Degree(A) + Degree(B)
Now we have a table with two identical columns. We can eliminate one (or both) by projecting.
The credentials belong to Groening.
Do I throw out people even if I don’t have any credentials for them?
There are different types of joins.