如何同步以前删除的行

Question

I have a junction/ many to many table in my database. This table has 2 columns forming a composite primary key; userid & groupid.

I'm having an issue where once a row is deleted it can never be re-added and synced again. For example:

1. user 123 is added to group 456 changes synchronized, upload direction. Row is added to remote.
2. user 123 removed from group 456 (row tombstoned in table meta and row removed from base table)
3. changes synchronized, upload direction. Row is removed on remote
4. user 123 is added to group 456
5. changes synchronized, upload direction. Row is not inserted in remote.

I'm guessing that the scope knowledge is retaining the fact that the row was once deleted and not syncing changes to it? Is this understanding correct? Is there anyway to clean this knowledge?

Answer 1

If any of key columns have IDENTITY property set, then you cannot simply insert values in such column. You should use this property wisely - its idea it to ensure keys are never repeated.

So if you really need to insert values into IDENTITY column use SET IDENTITY_INSERT MyTable ON/OFF . Only one table in a db can have this property set to ON. If it is off - an error occurs.

CREATE TABLE MyTable (ID INT IDENTITY NOT NULL)
SET IDENTITY_INSERT MyTable ON/OFF
INSERT INTO MyTable VALUES (2)
SET IDENTITY_INSERT MyTable ON/OFF