How To Interpolate Literal Strings?

You can use inline val (literal type) string values in your queries:

inline val columns = "id, name, age"
sql"""
  SELECT ${columns}
  FROM customers
""".readRows[Customer]()

This will not make a ? parameter, it will directly insert the literal string.
Same as if you wrote this:

sql"""
  SELECT id, name, age
  FROM customers
""".readRows[Customer]()