Hi,
I am making changes to an existing database while developing new software. There is also quite a lot of legacy software that uses the database that needs to continue working, i.e. I would like to maintain the existing database tables, procs, etc.
Currently I have the table
CREATE TABLE dbo.t_station ( tx_station_id VARCHAR(4) NOT NULL, tx_description NVARCHAR(max) NOT NULL, tx_station_type CHAR(1) NOT NULL, tx_current_order_num VARCHAR(20) NOT NULL, PRIMARY KEY (tx_station_id) )
I need to include a new field in this table that refers to a Plant (production facility) and move the tx_current_order_num to another table because it is not required for all rows. So I've created new tables:-
CREATE TABLE Private.Plant ( PlantCode INT NOT NULL, Description NVARCHAR(max) NOT NULL, PRIMARY KEY (PlantCode) ) CREATE TABLE Private.Station ( StationId VARCHAR(4) NOT NULL, Description NVARCHAR(max) NOT NULL, StationType CHAR(1) NOT NULL, PlantCode INT NOT NULL, PRIMARY KEY (StationId), FOREIGN KEY (PlantCode) REFERENCES Private.Plant (PlantCode) ) CREATE TABLE Private.StationOrder ( StationId VARCHAR(4) NOT NULL, OrderNumber VARCHAR(20) NOT NULL, PRIMARY KEY (StationId) )
Now, I don't want to have the same data in two places so I decided to change the dbo.t_station table into a view and provide instead of triggers to do the DELETE, INSERT and UPDATE. No problem I have [most of] them working.
My question regards the INSTEAD OF UPDATE trigger, updating the Primary Key column (tx_station_id) and updates to multiple rows.
Inside the trigger block, is there any way to join the inserted and deleted [psuedo] tables so that I know the 'before update primary key' and the 'after update primary key'? Something like this...
UPDATE sta SET sta.StationId = ins.tx_station_id FROM Private.Station AS sta INNER JOIN deleted AS del INNER JOIN inserted AS ins ON ROW_IDENTITY_OF(del) = ROW_IDENTITY_OF(ins) ON del.tx_station_id = sta.StationId
At this stage I've put a check in the trigger block that rollbacks the update if the primary key column is updated and there is more than one row in the inserted, or deleted, table.