T-SQL：合并或向上插入子表

Question

I have three tables with data as shown in the following screenshot:

I have a working MERGE statement for the Users table that is sent to the SQL Server from C#. The MERGE statement correctly merges data into the ICS_USERS table. The #temp table is also created and populated in C#:

MERGE INTO ICS_Users AS Target 
USING #temp AS Source ON TARGET.USerID = Source.UserId 

WHEN MATCHED THEN 
    UPDATE 
    SET TARGET.UserName = Source.UserName, TARGET.Active = Source.Active 

WHEN NOT MATCHED THEN 
    INSERT(UserName, Active, UserInitials) 
    VALUES(Source.UserName, Source.Active, Source.UserInitials)

I want to allow the user to add/change/delete the role for a user and send in the MERGE statement to handle it. Note that the user will only ever be allowed to change a single user at one time.

How do I change the merge statement to account for the Role and User/Role associative table?

Answer 1

You can follow these steps to achieve this.

1. Create a stored procedure which will accept all the input parameters which are required to join, insert, update and delete the values using source and target. Make all parameter optional or null able so that you can run your merge even without input values.

2. Insert all these values in a table variable which will have same column as your target tables along with the same data type.

3. Use your actual source table and along with table variable and union them and then use the output in merge logic.

This will handle your both requirement in single merge statement. Even when you input columns will be null first query in union will always have values to suffice the merge logic.

Try if this will not work comment and I will provide you sql script. Here I am not providing sql intentionally so that at least you can read and try by your self and write the logic in sql.