That suggestion is based on this sentence:
Hendra Kurniawan wrote:We only need to modify the builder class if database vendor changes, quite convenient (at least to me).
You might well need to support two database vendors during the transition (the old one in the prod environment, the new one in dev/test environments). That would mean to shuffle the builder class code around for builds/deployments to different environments.
The factory method I've suggested would allow you to support both vendors in your code base, and choose the proper implementation at runtime (based on property file created during build, for example, or even dynamically by identifying the vendor of the JDBC driver used). In any case, the logic would be contained in the factory. That is not possible with static methods, of course.