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SQL Set Operators

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                                      ...
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SQL Set Operators

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 
                                            AS FirstName, FacLastName 
                                            AS LastName, FacCity 
                                            AS City, FacState 
                                            AS State 
                FROM Faculty 
                                    UNION 
                SELECT StdNo AS PerNo, StdFirstName 
                                            AS FirstName, StdLastName AS LastName, StdCity 
                                            AS City, StdState 
                                            AS State 
                FROM Student;

        Example 2: Show teaching assistants, faculty who are students.  Only show the common columns in the result.

                SELECT FacNo AS PerNo, FacFirstName 
                                           AS FirstName, FacLastName 
                                           AS LastName, FacCity 
                                           AS City, FacState 
                                           AS State 
                FROM Faculty 
                            INTERSECT 
                SELECT StdNo 
                                           AS PerNo, StdFirstName 
                                           AS FirstName, StdLastName 
                                           AS LastName, StdCity 
                                           AS City, StdState 
                                           AS State 
                FROM Student;

        Example 3: Show faculty who are not students (only faculty).  Only show the common columns in the result.

                SELECT FacNo AS PerNo, FacFirstName 
                                           AS FirstName, FacLastName 
                                           AS LastName, FacCity 
                                           AS City, FacState 
                                           AS State 
                FROM Faculty 
                                    MINUS 
                SELECT StdNo 
                                           AS PerNo, StdFirstName 
                                           AS FirstName, StdLastName 
                                           AS LastName, StdCity 
                                           AS City, StdState 
                                           AS State 
                FROM Student;

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