Ado. Net concurrency

1. Live later
Only the primary key is included in the where condition for update and deletion. For example:
User A reads a row
User B reads the same row
User B modifies this line and successfully submits changes
User a modified this line and successfully submitted the changes, covering the changes just submitted by user B.

2. Full field comparison
The where condition for update and deletion includes all fields, which can prevent future occupation. BLOB fields cannot be compared.

3. The where conditions for update and deletion include primary key and timestamp columns (timestamp columns must be added to the Table). The same as 2, the where condition can be simplified.

4. When primary keys and columns to be updated are used, different users can update different columns at the same time without overwriting each other.