I'm creating some tables using a Local based database in Visual Studio and I have 2 tables : DBAppointment (parent) and DBPatient (child).
What I'm trying to do is to specify the on delete cascade action (so when I'm deleting a record from the child table, the parent table record containing the id of the child table record should be removed) but I can't really find where this option is.
Any idea?
Read this Microsoft article first. Read Me. I use the GUI during design so here is a picture of how it is selected in SSMS.
The syntax added to the foreign key is " ON DELETE CASCADE "
Hope this will be useful for you.
If you're using Entity Framework with Code First Approach in your EfContext you can set .WillCascadeOnDelete(true);
See Working With Cascade Delete
Related
I am using Entity Framework version 4.0, I want to delete one column from the .edmx model. Because my development database contains one newly added column and my server database still doesn't have that column right now. So how can I solve this issue while publishing my code to my server?
You should always have a version of the published code and the database model that belong to that code.
In the model, if you select the column in the table you can right click and choose "delete from model" which remove the column
The Entity data model can not be auto-updated so when making changes on the database you have to update the .edmx by :
Right click on the diagram -> Update model from database -> select 'Add' then 'tables' finally on button 'Finish'.
Tell us if it's resolved.
I had created new tables but when I click update model from database, the new tables werent added. I tried setting primary keys and all, but it couldnt work too. And when I click the update model from database, in the dialog box, the "add" column, I selected Table but none of the tables stated there. So when I click finish, none of the new tables is being added to the model. I dont know why my tables not shown in the add column. Anyone know what is wrong with it?
Can't comment yet so I'll ask my question as an answer. Under the add tab, did you check the checkboxes for the table that you wanted to add? Secondly after you have added do you see your tables in the edmx file?
I dragged a view onto my dbml file and I am retrieving records from it. Upon modifying the records and calling context.SubmitChanges() no changes are sent back to the database. Upon debugging I saw that my context.ViewName.IsReadOnly is true.
Is there any way to change this? I can run sql update statements just fine in SSMS against the view, so I am unaware of why this wouldn't be possible.
Manually identifying the primary key in the dbml worked for me - just select the field that is mapped to the primary key from the source table and in its properties change 'Primary Key' to true.
I am writing my first database application in c# and I have to use MS Access database, I have two tables Invoice and Order the order table is a child table. Invoice is a parent table it has key column "InvoiceNumber" which is auto column and it has a one to many relation with Order table column "InvoiceNumber". The problem I am having is that I got an exception at the line
tableAdapterManager.UpdateAll(database1DataSet);
when I try to add a new row and click save,
"You cannot add or change a record because a related record is required in table 'Invoice'."
I tried to search but I am unable to find it any help for ms access database, most of them are of SQL database. I also found one solution to edit the relation in the dataset designer to select the option "Both relation and foreign key constraints" but it didnot work for me either.
Thanks
Make sure that your OleDbParameters are properly set and in the correct corresponding order as the columns in the tables in the database. If you use Visual Studio automated code generation for data sources when you add a database, then drag and drop a table onto a form, check out the <database name>DataSet.Designer.cs file. It will teach you all you need to know.
I am using ADO.NET Entity Data Model in my C# project. There is an ADO.NET Entity Data Model that is generated on the DB in my project. How do I quickly refresh the ADO.NET Entity Data Model based on DB changes? I have been deleting the model and then creating a new one. I believe that there is a more simple and quick way.
Right-click on the model designer and choose "Update Model from Database", and a dialog box will pop up. Click OK and your model will be refreshed.
FYI, I'm using EF 4.0, and I skipped the earlier version, so I can't tell you what it's like in VS 2008.
Update Model from Database doesn't work very well. At least in VS 2008/C# 3.5. I fails to remove old columns, etc.
I always Ctrl-A (to select everything), the press delete, and then create model from database from scratch - update just doesn't work right in a lot of cases. At least in EF4 / VS2010 that I am developing in/with.
Perhaps this helps... Update Model Wizard (Entity Data Model Tools)
You should open your Model.edmx after that right click on the properties. now select the (Update Model from Database) and it will going to show you another panel with tab panel. you can choose Add,Refresh and delete. in your current situation, you should select Refresh. then select Tables->dbo->and name of your table in database and then click finish. that's it. you've refresh your table.
but sometimes you can see in your model that something went wrong because the column is not in right position. to solve that just right click the column name and select 'UP' to move it up or 'DOWN' to bring it down.
i hope that it will help.
Right click - Update Model from Database.