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Overview

Simple embedded DSL for making SQL-like queries. Now supports SELECT, INSERT, UPDATE and DELETE commands.

Working with DSL

Defining entities

Define "user" entity with "id" and "name"

(define-entity user
   user_table  ; DB table name
   (id name))  ; fields list

Defining connection

Connection used implicitly to execute all commands

(define-current-connection
  #:database "test"
  #:password "test"
  #:user "test")

Making queries

Select queries has following format

(select ENTITY [where CONDITIONS] [order-by FIELD asc/desc])

For example

(select user)  ; SELECT id,name FROM user_table
(select user [where (and (> id 1) (< id 3))])  ; SELECT id,name FROM user_table WHERE ((id > '1') and (id < '3'))
(select user [order-by name asc])  ; SELECT id,name FROM user_table ORDER BY name ASC

Select returns list of user structs. User field can be accessed with standard struct selectors (user-id, user-name)

(define (print-users user-list)
  (for ([user user-list])
    (printf "Id: ~a, name: ~a\n" (user-id user) (user-name user))))

Insert/Update

Creating user

(insert user (user 1 "John Doe"))

Rename user

(define (rename-user target-user new-name)
  (update user (struct-copy user target-user [name new-name])))

Delete

You can delete entity instance after selecting it.

(define (delete-user-by-id id)
  (let ([selected-user (first (select user [where (= id id)]))])  ; assuming, that user with given id exists
    (delete user selected-user)))