Clojure / SQLServer: How to Call Stored Procedure with C3P0 Connection Pool

Question

Following this example

https://github.com/clojure/java.jdbc/blob/master/doc/clojure/java/jdbc/ConnectionPooling.md

of jdbc connection pooling, I have set up a connection pool in a Clojure app to a SQLServer as follows

;; Database Connection Handling.
(ns myapp.db
    (:import [com.mchange.v2.c3p0 ComboPooledDataSource]))

;; ### specification
;; Defines the database connection parameters.
(def specification {
    :classname "com.microsoft.sqlserver.jdbc.SQLServerDriver"
    :subprotocol "sqlserver"
    :subname "//some;info;here"
})

;; ### pooled-data-source
;; Creates a database connection pool using the
;; <a href="https://github.com/swaldman/c3p0">c3p0</a> JDBC
;; connection pooling library.
(defn pooled-data-source [specification]
    (let [datasource (ComboPooledDataSource.)]
        (.setDriverClass datasource (:classname specification))
        (.setJdbcUrl datasource (str "jdbc:" (:subprotocol specification) ":" (:subname specification)))
        (.setUser datasource (:user specification))
        (.setPassword datasource (:password specification))
        (.setMaxIdleTimeExcessConnections datasource (* 30 60))
        (.setMaxIdleTime datasource (* 3 60 60))
        {:datasource datasource}))

;; ### connection-pool
;; Creates the connection pool when first called.
(def connection-pool
    (delay
        (pooled-data-source specification)))

;; ### connection
;; Get a connection from the connection pool.
(defn connection [] @connection-pool)

I get how to use the connection to make select and insert statements etc, my question is how would I use it to call a stored procedure and collect the output, which may be records of various shapes and sizes?

;; ### Definitions of queries.
(ns myapp.query
     (:require [myapp.db]))

;; HOW DO I CALL THIS PROC THROUGH A POOLED CONNECTION?
(defn call-the-stored-proc []
    (str "{ call someStoredProcForMyApp("...")}"))

Answer 1

For basic stored procedures that don't require OUT parameters, you can use db-do-prepared.

(require '[clojure.java.jdbc :as j])
(j/db-do-prepared (connection) "EXEC YourStoredProc ?" [COLUMN_NAME])

It calls your connection function, which is the same one that the documentation says to call.

I've started working on adding full callable statement support to JDBC, but I haven't had the time to finish the work. It is issue JDBC-48 in Clojue's JIRA, and my progress is in the sprocs branch of my fork.