22- HAVING in SQL

El HAVING se agrego a SQL para solucionar el problema de WHERE en sitio onde no puede ser agregado

Sintaxis de HAVING

SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
HAVING condition
ORDER BY column_name(s);
    

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Ejemplos de HAVING

La seguiente instrucion enumera la cantidad de clientes en cada pais onde el numero sea mayor que 5

 SELECT COUNT(CustomerID), Country
 FROM Customers
 GROUP BY Country
 HAVING COUNT(CustomerID) > 5;
    

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Esta instrucion es igual a la anterior, pero ordena los paises de mayor a menor

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
HAVING COUNT(CustomerID) > 5
ORDER BY COUNT(CustomerID) DESC;
    

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Esta instrucion enumera los empleados con mas de 10 pedidos

SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders
FROM (Orders
INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID)
GROUP BY LastName
HAVING COUNT(Orders.OrderID) > 10;
    

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Esta instrucion enumera los empleados Julio y Manolo si registraran mas de 25 pedidos

        SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders
        FROM Orders
        INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID
        WHERE LastName = 'Julio' OR LastName = 'Manolo'
        GROUP BY LastName
        HAVING COUNT(Orders.OrderID) > 25;
    

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