gistfile1.clj

(defn deregister [write-db]
  (let [the-right-driver (java.sql.DriverManager/getDriver (format "jdbc:%s:%s" (:subprotocol write-db) (:subname write-db)))]
    (doseq [driver (enumeration-seq (java.sql.DriverManager/getDrivers))
            :when (not= (class driver) (class the-right-driver))]
      (java.sql.DriverManager/deregisterDriver driver))))

(defn postgres? []
  (every? #(instance? org.postgresql.Driver %)
          (enumeration-seq (java.sql.DriverManager/getDrivers))))

(defn hypersql? []
  (every? #(instance? org.hsqldb.jdbc.JDBCDriver %)
          (enumeration-seq (java.sql.DriverManager/getDrivers))))

> (deregister {:classname   "org.hsqldb.jdbcDriver"
              :subprotocol "hsqldb"
              :subname     (str "mem:" (java.util.UUID/randomUUID) ";shutdown=true;hsqldb.tx=mvcc;sql.syntax_pgs=true")})
;=> nil
> (postgres?)
;=> false
> (hypersql?)
;=> true