What is the root error "Could not establish a connection to the database. Check the connection string, username and password."

Looking through google and stackoverflow, I found several questions asking about "Could not connect to the database. Check the connection string, username and password." However, I cannot find anyone to find what is the main mistake.

I am trying to write my first Google script with a database connection; I have mysql and oracle jdbc getConnection, both of which raise this error. I checked, double- and thrice checked connection information to no avail. I know that databases are available (they can be entered through other clients from several different computers, such as php on a Linux box, an SQL developer on different Windows computers at home and at work). How do I determine what is the real mistake? The error presented to me is too general and abstract.

Environment: using the script in a Google spreadsheet (thus inheriting from any environment installed by Google). I am trying to use the Google jdbc API and no longer know about environment variables.

Using the following syntax:

var url = "jdbc:mysql://mysql.cb-pta.com:3306/u4lottery";
var conn = Jdbc.getConnection(url, user, password); 

Again, the user and password have been verified.