http://www.cnblogs.com/houwei... After reading this article, I still don’t understand what this statement does. It is during the execution of the specified query statement. This query statement involves Are all rows locked when you arrive? Then other operations (such as UPDATE) must wait for this query statement to end before they can continue to execute, right?

And what does the statement SELECT ... LOCK IN SHARE MODE mean? Why do some articles say that it should be avoided as much as possible under InnoDB?