squee's Introduction

squee

A refreshed JDBC wrapper, made for Clojure 1.7

Rationale

tl;dr:

Ergonomics: consistent argument shapes
Modernized implementation with cheap reducible result-sets
Less seq and stack frame allocation compared to clojure.java.jdbc
Smaller methods, modularized. (e.g. RowGenerator protocol)

Guide

Arguments

Arguments all have the same shape [conn sql params opts], and the first two are required.

conn: a connection or transaction
sql: a SQL string
params: a function that manipulates the sql statement, usually filling in templated values. There are two such built-ins, params and many. See below
opts: a map of options

Examples

Full API docs

Query

(query conn "select * from bar")

(query conn "select * from bar where x = ?" (params 4))

Inserts

(let [sql "insert into foo (x,y) values (?,?)"]
  (execute! conn sql (params 42 40) {:return-keys? true}))

(let [sql "insert into foo (x,y) values (?,?)"]
  (execute! conn sql (many [[20 30] [40 50]])))

Transactions

(transactionally conn
  (execute conn ...)
  (query conn...)
  (execute conn...))

You can set the isolation level like so:

(transactionally conn {:isolation-level :serializable}
  ...body)

Param Helpers

Statement params come in two flavors, one or many, dependending on how many times the entire sql statement is used

(params ...)
(many [ [...] [...] [...] ...])    ;; this can be an lazy or an eduction too

Reducible Result sets

While clojure.java.jdbc uses lazy-seqs and a naive strategy to extract data from a ResultSet, results from query in this library implement clojure.lang.IReduceInit, and are very efficient to realize.