Database credentials inside client

Hello everybody. I was making an online game and I was performing the database.
Looking around the forum and here I saw a lot of people speaking about php and JSON requests.
I found a new plugin called “MYSQLConnectorUE4 Plugin” that make a connection between database using blue prints.
My quesion is: is this way secure for my credentials of the database? Can’t somebody stole that after that I package the game?
Thank you.