If you still have issues, then create a test project and post the links here. But if you need 1:m then the inserts should happen into both parent and child tables be committed all at once. Whether you want to have 1:0/m or 1:m depends on your requirement. Trains (IdTrain) => 1:0/m => ExTrains (IdTrain) If it is a large system then I try to get the last ID values at the time of INSERT operation. If it is a small system I maintain a list of last ID values in memory which are set at the beginning of the app. Personally I don't prefer Autoincremented IDs. Never declare many-to-many even with cascade operations enabled. In order to alleviate the complexities to maintain data integrity in transaction management it is important to keep the FK relationships simple one-to-zero/more (1:0/m) or one-to-one/more (1:m). Not all DBMSs offer good transaction management. In practical situations I have seen partial updates resulting mainly due to poor error management and improper rollbacks when errors occur. The problem comes at what stage the integrity errors occur. But if you don't define FKs soon the data will be out of sink and messy. Thx a lot for your answers ! I appreciate.ĭeclaring FKs in database helps in keeping data integrity but creates nightmare for transaction processing.
I'm little bit lost if you want to know :/ May be because : I will not be adding the FK to Trains from Ex as the actual relationship is M2M If my entry "Ex" already exist in my db, but I want to insert StatsEx and Trains, this is the problem. The only problem is when I get my table "Ex" or "Trains", I have only 1 child. I created my tables manually, adding a C# classe with the content you can see above.Īctually, I don't have any errors when I try to insert. I used a tool only to show you my tables ! This is why the names differ, because I did it fast. I didn't use a tool ! I created the tables manually. It will not be more difficult to dig more into it.
But let me know more details about issue. Long time since I generated physical databases from Entity Models. If so what is that error text?Īlso why the names differ between your Entitiy & Physical models? Were the names in physical database generated by the tool that you are using? So I think you are getting some error while inserting data. Then insert into the MEM resolving table ExTrains as needed. If that FK is removed, then you should be able to insert into Trains and Ex independently. But if I created the tables manually, I will not be adding the FK to Trains from Ex as the actual relationship is M2M. It appears you have created the tables using a tool. You have already resolved it by creating the ExTrains table. User393640 The main trouble spot in your database is the M2M relationship.
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