Question

问题：（请参阅下面的构建脚本，工作站属于卫星，卫星属于群组）

我正在尝试在工作站所属的组上更改组号时更新Station表的硬件描述符。最终，这将成为一个触发器。但是，我的更新语句正在影响工作站表的所有行，我只是不明白为什么。

下面的Try＃1和Try＃2都更新了站表中的每一行，而不仅仅是属于组的行（Id = 2）。

（ps。请原谅命名约定，这是我继承的数据库）

尝试＃1：

DECLARE  @insertedID BIGINT = 2

UPDATE STA SET
HardwareDescriptor  = CONVERT(nvarchar(10),G.GroupNum) + '-'
                    + CONVERT(nvarchar(10),SAT.SatelliteNum) +  '-'
                    + CONVERT(nvarchar(10),STA.StationNum)

FROM Station STA
    INNER JOIN Satellite SAT ON STA.SatelliteID = SAT.SatelliteID
    INNER JOIN [Groups] G ON SAT.GroupID = SAT.GroupID      

WHERE G.GroupId = @insertedID

尝试＃2：

DECLARE  @insertedID BIGINT

SET @insertedID = 2

UPDATE Station SET
HardwareDescriptor  = CONVERT(nvarchar(10),STA.GroupNum) + '-'
                    + CONVERT(nvarchar(10),STA.SatelliteNum) +  '-'
                    + CONVERT(nvarchar(10),STA.StationNum)

FROM (SELECT STA.StationId, SAT.SatelliteID, G.GroupId,
             STA.StationNum, SAT.SatelliteNum, G.GroupNum
             FROM Station STA
                INNER JOIN Satellite SAT ON STA.SatelliteID = SAT.SatelliteID
                INNER JOIN [Groups] G ON SAT.GroupID = SAT.GroupID
                AND G.GroupId = @insertedID) STA

WHERE STA.StationId = Station.StationId

构建脚本：

IF OBJECT_ID('Station') IS NOT NULL
DROP TABLE Station;
GO
IF OBJECT_ID('Satellite') IS NOT NULL
DROP TABLE Satellite;
GO
IF OBJECT_ID('Groups') IS NOT NULL
DROP TABLE Groups;
GO
CREATE TABLE Groups
(
GroupId INT NOT NULL PRIMARY KEY,
GroupNum INT NOT NULL
);
CREATE TABLE Satellite
(
SatelliteId INT NOT NULL PRIMARY KEY,
SatelliteNum INT NOT NULL,
GroupId INT FOREIGN KEY REFERENCES Groups(GroupId)
);

CREATE TABLE Station
(
StationId INT NOT NULL PRIMARY KEY,
HardwareDescriptor NVARCHAR(20),
StationNum INT NOT NULL,
SatelliteId INT FOREIGN KEY REFERENCES Satellite(SatelliteId)
);
INSERT INTO Groups (GroupId, GroupNum) VALUES 
(1, 1), (2, 2), (3,3)
INSERT INTO Satellite (SatelliteId, SatelliteNum, GroupId) VALUES
(1, 1, 1), (2, 2, 1), (3, 3, 2), (4, 4, 2);
INSERT INTO Station (StationId, SatelliteId, StationNum) VALUES
(1, 1,1 ), (2, 1, 2), (3,1, 3), (4, 2, 4), (5,2, 5), (6, 3, 6), (7,3, 7),      (8,3, 8), (9,3, 9);

Answer 1

在你第一次尝试这一行时：

INNER JOIN [Groups] G ON SAT.GroupID = SAT.GroupID

应该是

INNER JOIN [Groups] G ON SAT.GroupID = G.GroupID

我认为纠正这种联接应该可以解决问题。第二次尝试在用作源派生表的查询中遇到同样的问题。

SQL Update，更新所有行（MS-SQL 2008）

1 个答案: