How to Use UPDATE nowait in oracle

1. UPDATE nowait: query a piece of data and enable database transactions for it. If no lock is applied to the current data, the system returns the correct result and locks the current data. If the queried data is already in the transaction, the system locks the data. However, an error message is returned, indicating that the data has been locked. SQL statement:

SQL code:

SELECT *

FROM hold_mc_site_product_pic pic

WHERE image. id = 730127 for update nowait

2. Concurrent applications with multiple threads. First, the data to be processed is queried, and database-level locks are added. After processing, the data is written to the database. Commit a transaction. It can effectively control data consistency in the case of concurrency.