| Copyright | (c) 2011 MailRank Inc. (c) 2011-2012 Leon P Smith (c) 2012-2013 Janne Hellsten |
|---|---|
| License | BSD3 |
| Maintainer | Janne Hellsten <jjhellst@gmail.com> |
| Portability | portable |
| Safe Haskell | None |
| Language | Haskell2010 |
Database.SQLite.Simple.Types
Description
Top-level module for sqlite-simple.
Documentation
A placeholder for the SQL NULL value.
Constructors
| Null |
A single-value "collection".
This is useful if you need to supply a single parameter to a SQL query, or extract a single column from a SQL result.
Parameter example:
query c "select x from scores where x > ?" (Only (42::Int))Result example:
xs <- query_ c "select id from users"
forM_ xs $ \(Only id) -> {- ... -}A query string. This type is intended to make it difficult to construct a SQL query by concatenating string fragments, as that is an extremely common way to accidentally introduce SQL injection vulnerabilities into an application.
This type is an instance of IsString, so the easiest way to
construct a query is to enable the OverloadedStrings language
extension and then simply write the query in double quotes.
{-# LANGUAGE OverloadedStrings #-}
import Database.SQLite.Simple
q :: Query
q = "select ?"The underlying type is a Text, and literal Haskell strings that
contain Unicode characters will be correctly transformed to UTF-8.
A composite type to parse your custom data structures without having to define dummy newtype wrappers every time.
instance FromRow MyData where ...
instance FromRow MyData2 where ...
then I can do the following for free:
res <- query' c "..."
forM res $ \(MyData{..} :. MyData2{..}) -> do
....
Constructors
| h :. t infixr 3 |