SQL Set Operators Traditional Set Operators: Union Compatibility: Requirement for the traditional set operators. Strong requirement. - Same number of columns. - Each corresponding column is compatible. - Positional correspondence. Apply to similar tables by removing columns first. SQL UNION Example: Example 1: Retrieve basic data about all university people. SELECT FacNo AS PerNo, FacFirstName ...
Join Operation Using SELECT Statement
Cross Product Style:
- List tables in the FROM clause.
- List join conditions in the WHERE clause.
Example:
SELECT OfferNo, CourseNo, FacFirstName, FacLastName
FROM Offering, Faculty
WHERE OffTerm = 'FALL'
AND OffYear = 2016 AND FacRank = 'ASST'
AND CourseNo LIKE 'IS%'
AND Faculty.FacNo = Offering.FacNo;
Join Operator Style:
- Use INNER JOIN and ON keywords.
- FROM clause contains join operations.
Example:
SELECT OfferNo, CourseNo, FacFirstName, FacLastName
FROM Offering INNER JOIN Faculty
ON Faculty.FacNo = Offering.FacNo
WHERE OffTerm = 'FALL'
AND OffYear = 2016
AND FacRank = 'ASST'
AND CourseNo LIKE 'IS%';
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