upsert support

[fwbrasil]

Quill requires multiple queries to use the upsert (insert or update) pattern:

case class Person(name: String)

val count = quote {
  (name: String) => query[Person].filter(_.name == name).size
}
val insert = quote {
  (name: String) => query[Person].insert(_.name -> name)
}
val update = quote {
  (name: String) => query[Person].update(_.name -> name)
}

db.transaction {
  if(db.run(count) == 0)
    db.run(insert)
  else
    db.run(update)
}

It should support a single upsert statement:

val a = quote {
  (name: String) => query[Person].upsert(_.name -> name)
}
db.run(a)

• Verify if the supported databases (mysql and postgres for now) have support for upserts using a single and atomic sql statement. If not, we might need to redesign the change.
• Add a new trait similar to Insertable/Updatable
• Create a new action AST for it.
• Implement a parser for it.
• Change the actionUnliftable to support it. The Unliftable instances are responsible for reading the quoted AST when expanding them within another quotation.
• Change the actionLiftable to support it. Liftable instances are responsible for lifting the query AST to the quoted instance.
• Fix the compilation warnings of pattern matching not considering the new AST type. Use the implementation for inserts as reference.
• Implement the integration between SqlIdiom and the specific dialect.

[dsounded]

any progress ?