I've put together two functions that handle this for me, and although
I haven't looked at recent changes to clojure.contrib.sql (which sound
interesting), perhaps there might be some interest in what I've got.
The first function takes a database connection and a SELECT statement,
returning a function representing the PreparedStatement. That
function can be called with arguments representing the question-marks
in the original SELECT statement. (It tweaks any inbound
java.util.Date args into java.sql.Date, naively.)
(let [query (rl.database/prepare-query (connection) "SELECT * FROM foo
WHERE x = ? AND y > ?")]
(doseq [foo (query "BAR" 42)]
(println foo)))
I was going to try to rig up a function in the metadata for the
returned function that would close the PreparedStatement but had real
work to do with it, so....
The second function builds on this function: it takes SQL with keyword-
style placeholders (like ActiveRecord) and
returns a query function. This function accepts a map as its
argument, and sets the parameters of the PreparedStatement using the
values in the map. This works better (or more sanely) for complex
queries in which the same value is used for multiple placeholders.
Unlike ActiveRecord, however, this uses a PreparedStatement, and so
will not accept syntax like "AND some_field IN (:bunch_of_foos)",
which I believe (in AR) works because they don't prepare the statement
but generate the SQL on the fly.
;; Example of second query with keyword parameters
(let [query (rl.sql/prepare-query (connection)
"SELECT * FROM foo
WHERE (a = :x AND b > :y)
OR (a <> :x AND b <= :y)")]
(doseq [foo (query {:x "BAR" :y 42})]
(println foo)))
On Jan 9, 5:05 pm, Greg Harman <ghar...@gmail.com> wrote:
> Would someone mind posting an example of a parameterized query using
> clojure.contrib.sql? There are examples in the source of non-
> parameterized queries, and do-prepared is used to parameterize values
> for inserts, but I can't seem to get my form quite right for a query.
>
> thanks,
> Greg
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