Transakcje inf. podstawowe

Transkrypt

1 Transakcje inf. podstawowe! Rozpoczęcie transakcji " Explicit " Autocommit! Zakończenie transakcji " COMMIT " ROLLBACK " Implicit BEGIN TRANSACTION UPDATE savings... UPDATE checking... COMMIT TRANSACTION

2 Transakcje BEGIN TRANSACTION UPDATE savings SET amount = (amount - 100) WHERE custid = <Rollback transaction if if error> UPDATE checking SET amount = (amount + 100) WHERE custid = <Rollback transaction if if error> COMMIT TRANSACTION

3 Zmienne! DECLARE deklaruje zmienną! SET lub SELECT - nadaje wartość varchar(11) = 'Dodsworth' = FirstName FROM Northwind..Employees WHERE LastName + ' ' GO

4 Instrukcje warunkowe, pętle " BEGIN END blocks " IF ELSE blocks " WHILE constructs " CASE expression IF IF USER_NAME() <> <> 'dbo' BEGIN RAISERROR('Must be be sysadmin to to Perform Operation', 10, 10, 1) 1) RETURN END END ELSE ELSE DBCC DBCC CHECKDB(Northwind)

5 Dynamiczne konstruowanie poleceń! EXECUTE + string zawierający polecenie varchar(30) SET = 'Northwind' SET = 'Products' EXECUTE ('USE ' + ' SELECT * FROM '+

6 Procedury

7 Procedury (Stored Procedures)! Definiowanie procedur! Zalety

8 Stored Procedures - zalety! Umożliwiają definiowanie logiki aplikacji! Ułatwiają zarządzanie uprawnieniami! Poprawiają wydajność

9 Definiowanie procedur! Stored Procedure to skompilowna kolekcja poleceń Transact-SQL! Procedury: " mogą zawierać polecenia które manipulują danymi " mogą przyjmować dane w postaci parametrów " mogą zwracać wartość " mogą zwracać wartości w postaci parametrów

10 Tworzenie procedur! Polecenie CREATE PROCEDURE USE Northwind GO CREATE PROC dbo.overdueorders AS SELECT * FROM dbo.orders WHERE RequiredDate < GETDATE() AND ShippedDate IS Null GO! mogą być zagnieżdżone (do 32 poziomów)! sp_help pokazuje inf. o procedurze

11 Wykonanie procedury! Wykonanie EXEC OverdueOrders! Wykonanie w ramach polecenia INSERT INSERT INTO Customers EXEC EmployeeCustomer

12 Modyfikacja i usuwanie USE USE Northwind Northwind GO GO ALTER ALTER PROC PROC dbo.overdueorders AS AS SELECT SELECT CONVERT(char(8), CONVERT(char(8), RequiredDate, RequiredDate, 1) 1) RequiredDate, RequiredDate, CONVERT(char(8), CONVERT(char(8), OrderDate, OrderDate, 1) 1) OrderDate, OrderDate, OrderID, OrderID, CustomerID, CustomerID, EmployeeID EmployeeID FROM FROM Orders Orders WHERE WHERE RequiredDate RequiredDate < GETDATE() GETDATE() AND AND ShippedDate ShippedDate IS IS Null Null ORDER ORDER BY BY RequiredDate RequiredDate GO GO " usuwanie DROP PROC... " sp_depends pokazuje obiekty zależne

13 Procedury - parametry CREATE CREATE PROCEDURE PROCEDURE dbo.[year dbo.[year to to Year Year DateTime DateTime AS AS IS IS NULL NULL IS IS NULL NULL BEGIN BEGIN RAISERROR('NULL RAISERROR('NULL values values are are not not allowed', allowed', 14, 14, 1) 1) RETURN RETURN END END SELECT SELECT O.ShippedDate, O.ShippedDate, O.OrderID, O.OrderID, OS.Subtotal, OS.Subtotal, DATENAME(yy,ShippedDate) AS AS Year Year FROM FROM ORDERS ORDERS O INNER INNER JOIN JOIN [Order [Order Subtotals] Subtotals] OS OS ON ON O.OrderID O.OrderID = OS.OrderID OS.OrderID WHERE WHERE O.ShippedDate O.ShippedDate GO GO

14 Wywołanie procedury! Passing Values by Parameter Name EXEC EXEC = = 'Maria = 'Alfreds = 'Sales = 'Obere Str. Str. = = = = ' '! Passing Values by Position EXEC EXEC AddCustomer 'ALFKI2', 'Alfreds Futterkiste', 'Maria Anders', 'Sales Representative', 'Obere Str. Str. 57', 57', 'Berlin', NULL, NULL, '12209', 'Germany', ' '

15 Parametry wyjściowe Creating Stored Procedure Executing Stored Procedure Results of of Stored Procedure CREATE @m2 smallint OUTPUT AS AS SET GO GO smallint EXECUTE MathTutor OUTPUT SELECT 'The result is: is: ', The The result is: is: 30 30

16 Funkcje

17 Funkcje! Funkcje skalarne " Podobne do funkcji wbudowanych " Zwracają pojedynczą wartość! Multi-Statement Table-valued Functions " zawartość jak w przypadku stored procedures " odwołanie jak do widoku! In-line Table-valued Functions " podobne do widoków z parametrami

18 Funkcje! Tworzenie funkcji USE USE Northwind Northwind CREATE CREATE FUNCTION FUNCTION fn_newregion fn_newregion nvarchar(30)) nvarchar(30)) RETURNS RETURNS nvarchar(30) nvarchar(30) BEGIN BEGIN IS IS NULL NULL = 'Not 'Not Applicable' Applicable' END END

19 Funkcje! Modyfikacja funkcji ALTER ALTER FUNCTION FUNCTION dbo.fn_newregion dbo.fn_newregion <New <New function function content> content> " Uwaga: uprawnienia pozostają! Usunięcie funkcji DROP DROP FUNCTION FUNCTION dbo.fn_newregion dbo.fn_newregion

20 Scalar User-defined Function! Tworzenie USE USE Northwind Northwind CREATE CREATE FUNCTION FUNCTION fn_dateformat fn_dateformat char(1)) char(1)) RETURNS RETURNS Nchar(20) Nchar(20) AS AS BEGIN BEGIN RETURN RETURN + CONVERT(Nvarchar(20), @separator + CONVERT(Nvarchar(20), END END! Wywołanie SELECT SELECT dbo.fn_dateformat(getdate(), ':') ':')

21 Multi-Statement Table-valued Function! BEGIN and END nawiasy ograniczające! RETURNS określa definicję tabeli która ma być zwrócona

22 Multi-Statement Table-valued Function! Tworzenie USE USE Northwind Northwind GO GO CREATE CREATE FUNCTION FUNCTION fn_employees fn_employees nvarchar(9)) nvarchar(9)) table table (EmployeeID (EmployeeID int int PRIMARY PRIMARY KEY KEY NOT NOT NULL, NULL, [Employee [Employee Name] Name] nvarchar(61) nvarchar(61) NOT NOT NULL) NULL) AS AS BEGIN BEGIN = 'ShortName' 'ShortName' SELECT SELECT EmployeeID, EmployeeID, LastName LastName FROM FROM Employees Employees ELSE ELSE = 'LongName' 'LongName' SELECT SELECT EmployeeID, EmployeeID, (FirstName (FirstName + ' ' + LastName) LastName) FROM FROM Employees Employees RETURN RETURN END END! Wywołanie SELECT SELECT * FROM FROM dbo.fn_employees('longname') Or Or SELECT SELECT * FROM FROM dbo.fn_employees('shortname')

23 In-Line Table-valued Function! Treść funkcji stanowi polecenie SELECT! Nie używa nawiasów BEGIN END! RETURN specyfikuje zwracaną tablicę! Format (schemat) zwracanej tablicy jest określony przez format zbioru wynikowego

24 In-Line Table-valued Function! Tworzenie USE USE Northwind Northwind GO GO CREATE CREATE FUNCTION FUNCTION nvarchar(30) nvarchar(30) ) RETURNS RETURNS table table AS AS RETURN RETURN ( SELECT SELECT CustomerID, CustomerID, CompanyName CompanyName FROM FROM Northwind.dbo.Customers WHERE WHERE Region )! Wywołanie SELECT SELECT * FROM FROM fn_customernamesinregion(n'wa')

25 Trigery

26 Triggery - wprowadzenie! Trigger to procedura specjalnego typu! Trigger: " jest związany z tabelą " jest wywoływany automatycznie nie można go wywołać w sposób bezpośredni " jest częścią transakcji która go wywołała

27 Użycie trigerów! Automatyczne wykonywanie operacji na powiązanych tabelach! Zapewnienie warunków integralności! Obsługa błędów! Obsługa zdenormalizowanych danych

28 Trigery Use Use Northwind GO GO CREATE TRIGGER Empl_Delete ON ON Employees FOR FOR DELETE AS AS IF IF (SELECT COUNT(*) FROM FROM Deleted) > 1 BEGIN RAISERROR( 'You 'You cannot delete more more than than one one employee at at a time.', 16, 16, 1) 1) ROLLBACK TRANSACTION END END

29 Modyfikacja i usuwanie USE USE Northwind GO GO ALTER TRIGGER Empl_Delete ON ON Employees FOR FOR DELETE AS AS IF IF (SELECT COUNT(*) FROM FROM Deleted) > 6 BEGIN RAISERROR( 'You 'You cannot delete more more than than six six employees at at a time.', 16, 16, 1) 1) ROLLBACK TRANSACTION END END

30 Trigery! INSERT Trigger! DELETE Trigger! UPDATE Trigger! INSTEAD OF Trigger

31 Triggers - przykłady! Zapewnienie integralności danych! Business Rules

32 Zapewnienie integralności danych CREATE CREATE TRIGGER TRIGGER BackOrderList_Delete ON ON Products Products FOR FOR UPDATE UPDATE AS AS IF IF (SELECT (SELECT BO.ProductID BO.ProductID FROM FROM BackOrders BackOrders AS AS BO BO JOIN JOIN Inserted Inserted AS AS I ON ON BO.ProductID BO.ProductID = I.Product_ID I.Product_ID ) > 0 BEGIN BEGIN DELETE DELETE BO BO FROM FROM BackOrders BackOrders AS AS BO BO INNER INNER JOIN JOIN Inserted Inserted AS AS I ON ON BO.ProductID BO.ProductID = I.ProductID I.ProductID END END Products ProductID UnitsInStock Updated Trigger Deletes Row BackOrders ProductID UnitsOnOrder

33 Business Rules Products with Outstanding Orders Cannot Be Deleted Products IF IF (Select (Select Count Count (*) (*) FROM FROM [Order [Order Details] Details] INNER INNER JOIN JOIN deleted deleted ON ON [Order [Order Details].ProductID = deleted.productid ) > 0 ROLLBACK ROLLBACK TRANSACTION TRANSACTION DELETE statement executed on Product table ProductID UnitsInStock Trigger code checks the Order Details table Order Details OrderID ProductID UnitPrice Quantity Discount Transaction rolled back 'Transaction 'Transaction cannot cannot be be processed' processed' 'This 'This product product has has order order history' history'