Some understanding of the Select for update and update

Select ... The syntax for the FOR UPDATE statement is the same as the SELECT statement, except that the FOR UPDATE clause is appended to the SELECT statement.

The statement is used to lock a specific row, if there is a WHERE clause, which satisfies the where condition. When these rows are locked, other sessions can select the rows, but the rows cannot be changed or deleted until the statement's transaction is terminated by a commit statement or a ROLLBACK statement.

When a session uses update, an exclusive lock is added to the row, and other sessions need to wait for the update

This article is from the DBA Sky blog, so be sure to keep this source http://9425473.blog.51cto.com/9415473/1662798

Some understanding of the Select for update and update