MySQL HAV- klousule
Die MySQL HAVING-klousule
Die HAVINGklousule is by SQL gevoeg omdat die
WHEREsleutelwoord nie met totale funksies gebruik kan word nie.
HET Sintaksis
SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
HAVING condition
ORDER BY
column_name(s);Demo-databasis
Hieronder is 'n keuse uit die "Klante"-tabel in die Noordewind-voorbeelddatabasis:
| CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
|---|---|---|---|---|---|---|
| 1 |
Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
| 2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
| 3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 05023 | Mexico |
| 4 |
Around the Horn | Thomas Hardy | 120 Hanover Sq. | London | WA1 1DP | UK |
| 5 | Berglunds snabbköp | Christina Berglund | Berguvsvägen 8 | Luleå | S-958 22 | Sweden |
MySQL MET Voorbeelde
Die volgende SQL-stelling lys die aantal kliënte in elke land. Sluit slegs lande in met meer as 5 kliënte:
Voorbeeld
SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
HAVING COUNT(CustomerID) > 5;
Die volgende SQL-stelling lys die aantal kliënte in elke land, hoog na laag gesorteer (sluit slegs lande in met meer as 5 kliënte):
Voorbeeld
SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
HAVING COUNT(CustomerID)
> 5
ORDER BY COUNT(CustomerID) DESC;
Demo-databasis
Hieronder is 'n keuse uit die "Bestellings"-tabel in die Noordewind-voorbeelddatabasis:
| OrderID | CustomerID | EmployeeID | OrderDate | ShipperID |
|---|---|---|---|---|
| 10248 | 90 | 5 | 1996-07-04 | 3 |
| 10249 | 81 | 6 | 1996-07-05 | 1 |
| 10250 | 34 | 4 | 1996-07-08 | 2 |
En 'n keuse uit die "Werknemers"-tabel:
| EmployeeID | LastName | FirstName | BirthDate | Photo | Notes |
|---|---|---|---|---|---|
| 1 | Davolio | Nancy | 1968-12-08 | EmpID1.pic | Education includes a BA.... |
| 2 | Fuller | Andrew | 1952-02-19 | EmpID2.pic | Andrew received his BTS.... |
| 3 | Leverling | Janet | 1963-08-30 | EmpID3.pic | Janet has a BS degree.... |
Meer OM Voorbeelde te hê
Die volgende SQL-stelling lys die werknemers wat meer as 10 bestellings geregistreer het:
Voorbeeld
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;
Die volgende SQL-stelling lys as die werknemers "Davolio" of "Fuller" meer as 25 bestellings geregistreer het:
Voorbeeld
SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders
FROM Orders
INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID
WHERE LastName = 'Davolio' OR LastName = 'Fuller'
GROUP BY LastName
HAVING
COUNT(Orders.OrderID) > 25;