Answer:
Join
Explanation:
Five basic set operators in relational algebra are as follows:
- Selection - tuple selection
- Projection - extract columns
- Cartesian product - cross product of relations
- Set union - union of two relations
- Set difference - minus operation on two relations
As we can see, Join is not part of the basic set operations but it is implemented using the Cartesian Product operator.
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Answer and Explanation:
For returning four columns from the Invoices table, named Number, Total, Credits, and Balance the SELECt statement is as follows
Select Invoice Number As Number
Invoice Total As Total
Payment total + credit total As Credits
Invoice total
(Payment total + credit total) As Balance
These are displayed as above
Physical memory
Main memory refers to physical memory that is internal to the computer.
