Select statement for update

Select... The syntax of the For Update statement is the same as that of the select statement, but the for update [NOWAIT] clause is added after the select statement.

This statement is used to lock specific rows (if a where clause exists, it is the rows that meet the where condition ). When these rows are locked, you can select
These rows, but cannot be changed or deleted until the transaction of the statement ends with a commit or rollback statement.

Author "moon-yang85-gmail-com"