When to use FOR UPDATE in SQL Queries? [duplicate]

Question

Can anyone please tell the difference between the following sql,

SELECT * FROM TABLE

VS

SELECT * FROM TABLE FOR UPDATE

When and at what situation i need to use For Update

It is taking more time for getting the data if i use update and getting stopped. What is happening on Update to increase the time. Please tell me the entire process happening on this.

Answer 1

I think the sentence from the MariaDB / MySQL manual is self-explanatory:

If you use FOR UPDATE with a storage engine that uses page or row locks, rows examined by the query are write-locked until the end of the current transaction.