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Clojure.sql

Clojure library for making querying databases easier by writing your queries as SQL and transforming them into clojure functions.

Everything is work in progress. This is my first clojure project so comments are welcome. If you read the code (around 100 LOC) and have any recommendations please share them.

Usage

The library provides you with query function and 2 macros (defquery and defqueries-from-dir).

defquery

clojure.sql.core/defquery
([query-name db-spec sql] [query-name db-spec sql opts])
Macro
  Defines a query function using the given name

Macro defines a function for you that you can call with a map of parameters and values. Parameters are in SQL written as keywords (such as :myparam).

(require '[clojure.sql.core :refer [query defquery]])

(def db-spec {:subprotocol "postgresql"
              :subname "//127.0.0.1:5432/test"})


; define a query
(defquery material-on-stock             ; query name
          db-spec                       ; database specification
          ; SQL string
          "select part_no, quantity     
           from inventory_stock_levels
           where part_no in (:part-no)  
              and warehouse = :warehouse
           order by :part-no")

; use your defined query
; parameters are given in a map
(material-on-stock {:part-no [100024040 100024041] ; one can give multiple values
                    :warehouse "CC110"})

One can use the whole set of options for the jdbc/query see , ie:

:identifiers, :as-arrays?, :row-fn, and :result-set-fn
:return-keys, :result-type, :concurrency, :cursors, :fetch-size, :max-rows

Two additional options can be supplied:

:db-spec
:parser

db-spec takes, well, db-spec or DB connection so you can use the query in transaction, etc. Parser can be injected if you have any special needs with regard to parsing the raw SQL and it's parameter placeholders.

Example of using options:

(defquery valve-state
  db-spec
  "select datetime, tagname, value
  from discretehistory dh
  where timeResolution = :resolution
    and tagname in (:tags)"
  {:fetch-size 100 :as-arrays? true}) ; specify default options if any

(valve-state {:resolution 1000
              :tags ["HV1010_Open" "HV1011_Open"]}
             {:as-arrays? false}) ; now :as-arrays? overrides default
                                  ; from defquery, fetch-size is still 100

If you want to use SQL without parametrs but with query options, you must supply nil instead of parameter hash:

(defquery query-without-params "select * from tags")

(query-without-params nil {:as-arrays? true}) ; nil is important here!

defqueries-from-dir

clojure.sql.core/defqueries-from-dir
([db-spec dir-path])
Macro
  Defines query functions from files of raw SQL in the directory given
  
  Query names will be the filenames with underscores '_' replaced with dashes '-'
  and without the '.sql' extension:

    'my_query.sql' file transforms into 'my-query' function

If you have this tree structure:

resources
└── sql
    ├── production
    │   ├── daily_production.sql
    │   └── quality_by_product.sql
    └── sales
        ├── customer_credit_levels.sql
        └── sales_by_salespersons.sql

You can run defqueries-from-dir and get following queries:

(defqueries-from-dir db-spec "resources/sql/")

(daily-production ...)
(quality-by-product ...)
(customer-credit-levels ...)
(sales-by-salespersons ...)