SQL (my / postgre) samples should use Apache Connection Pooling

[lesv]

(optional/future) instead of DriverManager.getConnection,
connection pooling with commons-bcp : https://mvnrepository.com/artifact/org.apache.commons/commons-dbcp2

[jabubake]

@lesv : @kurtisvg is planning to address this in the coming quarters, but might be looking into hikari instead for Java.