我需要写一个T-SQL存储过程来更新一个表中的行。如果该行不存在,则插入它。所有这些步骤都由一个事务包裹着。
这是一个预订系统,所以它必须是原子的和可靠的。如果交易被提交并且航班被预订,它必须返回true。
我是T-SQL的新手,不确定如何使用"@@rowcount"。这就是我到现在为止写的东西。我走的路对吗?我相信这对你来说是个简单的问题。
-- BEGIN TRANSACTION (HOW TO DO?)
UPDATE Bookings
SET TicketsBooked = TicketsBooked + @TicketsToBook
WHERE FlightId = @Id AND TicketsMax < (TicketsBooked + @TicketsToBook)
-- Here I need to insert only if the row doesn't exists.
-- If the row exists but the condition TicketsMax is violated, I must not insert
-- the row and return FALSE
IF @@ROWCOUNT = 0
BEGIN
INSERT INTO Bookings ... (omitted)
END
-- END TRANSACTION (HOW TO DO?)
-- Return TRUE (How to do?)
这是我最近才不得不做的事情。
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[cjso_UpdateCustomerLogin]
(
@CustomerID AS INT,
@UserName AS VARCHAR(25),
@Password AS BINARY(16)
)
AS
BEGIN
IF ISNULL((SELECT CustomerID FROM tblOnline_CustomerAccount WHERE CustomerID = @CustomerID), 0) = 0
BEGIN
INSERT INTO [tblOnline_CustomerAccount] (
[CustomerID],
[UserName],
[Password],
[LastLogin]
) VALUES (
/* CustomerID - int */ @CustomerID,
/* UserName - varchar(25) */ @UserName,
/* Password - binary(16) */ @Password,
/* LastLogin - datetime */ NULL )
END
ELSE
BEGIN
UPDATE [tblOnline_CustomerAccount]
SET UserName = @UserName,
Password = @Password
WHERE CustomerID = @CustomerID
END
END