Optimised query for updating millions of record

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Java

SQL

MySQL

database

I have a query script that is an update sql query having regex_replace to update a specific string to the desired string in db. I have used prepared statement of Java to run this query in my script. Something like this:

String SQL="UPDATE query where created >= ?  and created < ?";
    PreparedStatement stmt = conn.prepareStatement(SQL);
    conn.setAutoCommit(false);
    stmt.setDate(1, new java.sql.Date(datecreated.getTime()));
    stmt.setDate(2, new java.sql.Date(datecreatedTill.getTime()));
    stmt.addBatch();
    System.out.println("Script start time: "+ new java.util.Date());
    result = stmt.executeBatch();
    conn.commit();

So, I have the following questions now:

1. Is it the correct way to use prepared statement to optimize the update I intend to use?
2. Also, I read that preparedstatement basically combines all the queries into one or optimize multiple sql queries being passed to the db. So, i don't know how this regex_replce update query will get optimised as it will be just one sql query running on multiple records.
3. Please suggest if this is not a correct approach then if there is a better approach I can use

What I have tried:

I have tried to look over internet but optimising update with regex_replace is nowhere on the internet.