Question

我希望能够为jdbc编写以下函数：

(def db {:classname "com.mysql.jdbc.Driver"
         :subprotocol "mysql"
         :subname "//127.0.0.1:3306/santacsv"
         :server "//127.0.0.1:3306"
         :schema "santa"
         :user "root"
         :password "root"})

(defn has-schema? [db & [schema]])

(defn create-schema [db & [schema]])

(defn drop-schema [db & [schema]])

我不确定该怎么做。任何帮助将不胜感激

Answer 1

至少，您可以使用clojure.java.jdbc并将相应的SQL写入execute!。

或者，我会考虑使用专用的迁移库/框架。 flyway是基于java的，有一个java-api，你可以用interop调用它。

最后，有一些基于clojure的迁移库，如lobos，但我不能说它们的成熟度，所以你的里程可能非常。

Answer 2

我在这里实现了自己：

https://github.com/zcaudate/manas/blob/master/src/manas/core.clj

    (defmacro run-statement [env database body catch-body & [statement]]
      `(do (Class/forName (:classname ~env))
           (let [~'conn (atom nil)]
             (try
               (reset! ~'conn (DriverManager/getConnection
                              (str "jdbc:" (:subprotocol ~env) ":"
                                   (:server ~env) "/" (or ~database (:database ~env)))
                              (:user ~env)
                              (:password ~env)))
               ~@(if statement
                   [(list 'let '[stmt (.createStatement @conn)]
                          (list '.executeUpdate 'stmt statement))])
               ~@body
               (catch SQLException ~'e
                 ~@catch-body)
               (finally
                 (if-not (nil? (deref ~'conn))
                   (.close (deref ~'conn))))))))

    (defn has-connection? [env & [url]]
      (let [env (if url (assoc env :server url) env)]
        (run-statement env "" (true) (false))))

    (defn all-databases [env]
      (run-statement env ""
                     ((let [rs (.getCatalogs (.getMetaData @conn))]
                        (loop [rs rs acc []]
                          (if (.next rs)
                            (recur rs (conj acc (.getString rs "TABLE_CAT")))
                            acc))))
                     ()))

    (defn has-database? [env & [schema]]
      (run-statement env schema (true) (false)))

    (defn create-database [env & [schema]]
      (run-statement env ""
                     (true)
                     (false)
                     (str "create database " (or schema (:database env)))))

    (defn drop-database [env & [schema]]
      (run-statement env ""
                     (true)
                     (false)
                     (str "drop database " (or schema (:database env)))))

如何使用clojure的java.jdbc创建数据库？

2 个答案: