Clojurians Log v2

Hi, is there a way to use boolean expressions in select statements in honeysql? like select (a.numeric_field > 100) AS over_threshold

@bertofer I think you have to use #sql/call in there, like this:

user=> (require '[honeysql.helpers :refer :all] '[honeysql.core :as h] '[honeysql.types :as sql])
...
nil
user=> (h/format (select [#sql/call [:> :a 100] :threshold]))
["SELECT a > ? AS threshold" 100]
user=> 

(without the #sql/call you get SELECT > AS a AS threshold which is obviously wrong -- and should at least blow up with an assert in the next version -- but ideally should not treat the expression as an alias in that position either!)

Yes is what I ended up doing, thanks @seancorfield! I was doing it like a fn call though, like (sql/call :> :a 100), can you explain what is the difference with #sql/call [:> :a 100]? What’s the meaning of # here? I’m a bit new to clojure yet 🙂

@bertofer # indicates a reader literal so #sql/call [:> :a 100] says "read the following form -- [:> :a 100] -- and treat it as a "sql/call" object...

Okei, thanks ! 🙂

The reader doesn't evaluate forms:

user=> #sql/call [:> (keyword "a") (* 10 10)]
#sql/call [:> (keyword "a") (* 10 10)]
user=> (h/format *1)
["keyword(?) > (? * ?)" "a" 10 10]
user=> (sql/call :> (keyword "a") (* 10 10))
#sql/call [:> :a 100]
user=> (h/format *1)
["a > ?" 100]
user=> 

There are pros and cons to both approaches.

For example

user=> #sql/call [:> :a (* :b 10)]
#sql/call [:> :a (* :b 10)]
user=> (h/format *1)
["a > (b * ?)" 10]
user=> 

(sql/call :> :a (* :b 10)) will fail trying to evaluate :b times 10 🙂