使用SQL建立触发器和存储器代码
时间: 2023-06-22 13:41:05 浏览: 66
建立触发器的代码示例:
```
CREATE TRIGGER trigger_name
BEFORE INSERT ON table_name
FOR EACH ROW
BEGIN
-- 触发器逻辑代码
END;
```
其中,`trigger_name`是触发器的名称,`table_name`是要在其上建立触发器的表名,`BEFORE INSERT`表示在插入操作之前触发,`FOR EACH ROW`表示对于每一行数据都会触发该触发器。
建立存储过程的代码示例:
```
CREATE PROCEDURE procedure_name (IN param1 INT, IN param2 VARCHAR(255))
BEGIN
-- 存储过程逻辑代码
END;
```
其中,`procedure_name`是存储过程的名称,`(IN param1 INT, IN param2 VARCHAR(255))`是输入参数列表,`BEGIN`和`END`之间是存储过程的逻辑代码。
注意,在使用SQL建立触发器和存储过程时,不同的数据库管理系统可能有不同的语法和规则,需要根据具体的系统进行调整。
相关问题
Sql Server 触发器触发器级联删除代码
触发器级联删除是指当一个表中的数据被删除时,与其相关联的其他表中的数据也会被自动删除。下面是一个 SQL Server 触发器级联删除的示例代码:
```
CREATE TRIGGER [dbo].[trg_Delete] ON [dbo].[Table1]
AFTER DELETE
AS
BEGIN
SET NOCOUNT ON;
DELETE FROM [dbo].[Table2] WHERE [dbo].[Table2].[Id] IN (SELECT [dbo].[Table1].[Id] FROM DELETED);
DELETE FROM [dbo].[Table3] WHERE [dbo].[Table3].[Id] IN (SELECT [dbo].[Table1].[Id] FROM DELETED);
END
```
这个触发器在 Table1 表中的数据被删除时触发,然后通过 IN 子查询将与其相关联的 Table2 和 Table3 表中的数据也自动删除。其中,DELETED 是一个临时表,用于存储被删除的数据。
火车售票系统课程设计sqlserver,包括相应的触发器和存储器的具体代码
这是一个比较大的课程设计,需要根据具体的需求和设计进行不同的实现。下面是一个简单的示例,仅供参考。
首先,我们需要创建一些基本的表格来存储信息,比如车次表、车站表、座位表、订单表等等。下面是一个可能的表格设计:
```
-- 车次表
CREATE TABLE Train (
TrainID int PRIMARY KEY,
TrainName nvarchar(50),
StartStationID int,
EndStationID int,
StartTime datetime,
EndTime datetime,
Price money
);
-- 车站表
CREATE TABLE Station (
StationID int PRIMARY KEY,
StationName nvarchar(50)
);
-- 座位表
CREATE TABLE Seat (
SeatID int PRIMARY KEY,
TrainID int,
StationID int,
SeatType nvarchar(50),
Price money,
TotalNum int,
RemainNum int,
CONSTRAINT FK_Seat_Train FOREIGN KEY (TrainID) REFERENCES Train(TrainID),
CONSTRAINT FK_Seat_Station FOREIGN KEY (StationID) REFERENCES Station(StationID)
);
-- 订单表
CREATE TABLE Order (
OrderID int PRIMARY KEY,
TrainID int,
StartStationID int,
EndStationID int,
SeatID int,
SeatType nvarchar(50),
Price money,
UserID int,
BuyTime datetime,
CONSTRAINT FK_Order_Train FOREIGN KEY (TrainID) REFERENCES Train(TrainID),
CONSTRAINT FK_Order_StartStation FOREIGN KEY (StartStationID) REFERENCES Station(StationID),
CONSTRAINT FK_Order_EndStation FOREIGN KEY (EndStationID) REFERENCES Station(StationID),
CONSTRAINT FK_Order_Seat FOREIGN KEY (SeatID) REFERENCES Seat(SeatID)
);
```
接下来,我们可以创建一些触发器和存储过程来实现一些特殊的逻辑。下面是一个可能的示例:
```
-- 在订单表中插入数据时,更新座位表中的余票数量
CREATE TRIGGER AfterInsertOrder ON Order
AFTER INSERT
AS
BEGIN
DECLARE @SeatID int, @RemainNum int
SELECT @SeatID = SeatID FROM inserted
SELECT @RemainNum = RemainNum FROM Seat WHERE SeatID = @SeatID
UPDATE Seat SET RemainNum = @RemainNum - 1 WHERE SeatID = @SeatID
END
-- 在订单表中删除数据时,更新座位表中的余票数量
CREATE TRIGGER AfterDeleteOrder ON Order
AFTER DELETE
AS
BEGIN
DECLARE @SeatID int, @RemainNum int
SELECT @SeatID = SeatID FROM deleted
SELECT @RemainNum = RemainNum FROM Seat WHERE SeatID = @SeatID
UPDATE Seat SET RemainNum = @RemainNum + 1 WHERE SeatID = @SeatID
END
-- 查询订单信息并计算总价
CREATE PROCEDURE GetOrderInfo
@OrderID int
AS
BEGIN
SELECT o.OrderID, t.TrainName, s1.StationName AS StartStation, s2.StationName AS EndStation,
se.SeatType, o.Price, u.UserName, o.BuyTime, se.Price * DATEDIFF(hour, t.StartTime, t.EndTime) AS TotalPrice
FROM [Order] o
JOIN Train t ON o.TrainID = t.TrainID
JOIN Station s1 ON o.StartStationID = s1.StationID
JOIN Station s2 ON o.EndStationID = s2.StationID
JOIN Seat se ON o.SeatID = se.SeatID
JOIN [User] u ON o.UserID = u.UserID
WHERE o.OrderID = @OrderID
END
```
当然,以上只是一个简单的示例,具体的实现还需要考虑更多的细节和逻辑。