MSSQL Trigger Update on column - sql-server

Question

I have 2 tables and I want table 1 to have a trigger that insert or update in table 2, but I'm not sure how to do that.
Table 1:
CREATE TABLE [dbo].[DevicePorts](
[ID] [int] IDENTITY(1,1) NOT NULL,
[IsInUse] [bit] NOT NULL,
)
Table 2:
CREATE TABLE [dbo].[DevicePortActivities](
[ID] [uniqueidentifier] NOT NULL,
[StartTime] [datetimeoffset](7) NOT NULL,
[EndTime] [datetimeoffset](7) NULL,
[FK_DevicePortID] [int] NOT NULL FOREIGN KEY REFERENCES DevicePorts(ID),
)
Start of my trigger:
CREATE TRIGGER PortInUse
ON DevicePorts
AFTER UPDATE
AS BEGIN
SET NOCOUNT ON;
IF UPDATE (IsInUse)
BEGIN
IF IsInUse = 1
THEN
INSERT INTO [dbo].[DevicePortActivities]
(
[ID]
,[StartTime]
,[EndTime]
,[FK_DevicePortID]
)
VALUES
(
NEWID(),
SYSDATETIMEOFFSET(),
null,
<DevicePortID>
)
ELSE
UPDATE [dbo].[DevicePortActivities]
SET EndTime = SYSDATETIMEOFFSET()
WHERE FK_DevicePortID = <DevicePortID> AND EndTime is null
END
END
END
GO
What I'm trying to do is when 'IsInUse' is modified it should insert a row into 'DevicePortActivities' or update.
Conditions are, if 'IsInUse' is true then it should insert a record, if it's false it should update the last record where 'EndTime' is null.

Answer 1

You need to treat inserted as a table. I'd suggest looking at MERGE for this (because different rows may have had different changes applied by a single UPDATE).
Something like:
CREATE TRIGGER PortInUse
ON DevicePorts
AFTER UPDATE
AS
BEGIN
SET NOCOUNT ON;
MERGE INTO [dbo].[DevicePortActivities] t
USING (select i.ID,i.IsInUse as NewUse,d.IsInUse as OldUse
from inserted i inner join deleted d on i.ID = d.ID) s
ON
t.FK_DevicePortID = s.ID
WHEN MATCHED AND t.EndTime is null AND NewUse = 0 and OldUse = 1
THEN UPDATE SET EndTime = SYSDATETIMEOFFSET()
WHEN NOT MATCHED AND NewUse = 1 and OldUse = 0
THEN INSERT ([ID]
,[StartTime]
,[EndTime]
,[FK_DevicePortID])
VALUES (NEWID(),
SYSDATETIMEOFFSET(),
null,
s.ID);
END

Answer 2

I found a solution for my question
CREATE TRIGGER [dbo].[PortInUse]
ON [dbo].[DevicePorts]
AFTER UPDATE
AS BEGIN
SET NOCOUNT ON;
IF UPDATE (IsInUse)
BEGIN
DECLARE #IsInUse bit;
DECLARE #PortID int;
SELECT #IsInUse = i.IsInUse FROM inserted i;
SELECT #PortID = i.ID FROM inserted i;
IF (#IsInUse = 1)
INSERT INTO [dbo].[DevicePortActivities]
(
[ID]
,[StartTime]
,[EndTime]
,[FK_DevicePortID]
)
VALUES
(
NEWID(),
SYSDATETIMEOFFSET(),
null,
#PortID
);
ELSE
UPDATE [dbo].[DevicePortActivities]
SET EndTime = SYSDATETIMEOFFSET()
WHERE FK_DevicePortID = #PortID AND EndTime is null;
END
END
I'm not sure if there is a better way to do this, but it's working.