Group By Having with Left Outer Join

CIS430/530

Sunnie Chung

Select D.Dnumber, E.dno, E.salary From Department D Left Outer Join Employee E

ON D.Dnumber = E.dno;

/*Count(*) count a tuple of the join result*/

Select D.dnumber, Count(*), SUM(E.salary)

From Department D Left Outer Join Employee E

ON D.Dnumber = E.dno Group By D.dnumber;

/* NULL as Group */ Select E.dno, Count(E.dno), SUM(E.salary)

From Department D Left Outer Join Employee E

ON D.Dnumber = E.dno Group By E.dno;

/*COUNT counts Duplicates*/

Select Count(E.dno) from employee E;

/*To COUNT Unique Values Only*/ Select Count(Distinct E.dno)

from employee E;

/*COUNT Does NOT count NULL values*/ Select Count(E.superssn)

from employee E;

Select D.dnumber, Count(E.dno), Sum(E.Salary)

From Department D Left Outer Join Employee E ON D.Dnumber = E.dno

Group By D.dnumber;

Select D.dnumber, Count(E.dno), Sum(E.Salary)

From Department D Left Outer Join Employee E

ON D.Dnumber = E.dno Group By D.dnumber

Having COUNT(E.dno) > 2;