https://github.com/annenkov/sql-dsl

https://github.com/annenkov/sql-dsl

Last synced: 9 days ago
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• Host: GitHub
• URL: https://github.com/annenkov/sql-dsl
• Owner: annenkov
• Created: 2020-01-25T18:26:34.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2020-01-25T18:26:50.000Z (almost 5 years ago)
• Last Synced: 2024-11-06T08:03:07.306Z (about 2 months ago)
• Language: Racket
• Size: 16.6 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.rst

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README

        
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)))