ScalaDB is a Scala library for connecting to and querying relational databases. It is created on top of JDBC.

ScalaDB is extensively tested on H2. It should work with MySQL and PostGreSQL as well, although not heavily tested on those databases.

Columns can be defined as:

 val STR = VARCHAR(255)
 val name = Col("NAME", STR)
 val age = Col("AGE", INT)
 val sal = Col("SAL", LONG)

Tables can be defined as:

 val users = Tab.withName("USERS").withCols(name, age, sal).withPriKey(name, age) 

Tables can be queried as:

 users.select(name, age).where(sal >= 2000).as(User(_))  

and

 users.aggregate(age.avg).where(sal >= 200).asLong 

More examples here.