(defn reduce-sql-vec
  "Takes an array of SQL statement vectors and combines
  them into a valid clojure.java.jdbc query vector. In each statement vector
  you can have parameters at the end just like a jdbc vector. Easier to show
  than explain:

  take this:
  [[\"SELECT * FROM dude\"]
   [\" WHERE id = ?\" 1]]

  and turn it into this:
  [\"SELECT * FROM dude WHERE id = ?\" 1]

  This makes it a little easier to manage queries with large numbers of params."
  [sql-vec]
  (reduce (fn [acc line]
            (-> acc
                (update 0 #(str % (first line)))
                (into (rest line))))
          []
          sql-vec))

;; Example
;;
;; Requires one to have a db namespace,
;; JDBC param coercion from java.time.Instant
;; and a task table with described columns.

(require '[clojure.java.jdbc :as sql]
         '[java-time :as jt]
         '[my.db :as db])

(defn sql-test
  [id sdt edt]
  [["WITH"]
   ["  totals AS ("]
   ["    SELECT"]
   ["      date_trunc('day', created_at) as dt,"]
   ["      count(1) as total"]
   ["    FROM"]
   ["      task"]
   ["    WHERE"]
   ["      id = ?" id]
   ["      AND created_at"]
   ["      BETWEEN ? AND ?" sdt edt]
   ["    GROUP BY"]
   ["      date_trunc('day', created_at)"]
   ["  )"]
   [" SELECT * from totals"]])

(def now (jt/instant))

(def a-while-ago
  (-> now (jt/minus (jt/days 1))))

(->> (sql-test 1234 a-while-ago now)
     (reduce-sql-vec)
     (sql/query db/db))

;; => ({:dt #object[java.time.Instant 0x7474a5fe "2018-07-18T00:00:00Z"], :total 2})