Query string type borrowed from
mysql-simple.
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.
The underlying type is a
ByteString, and literal Haskell
strings that contain Unicode characters will be correctly transformed
to UTF-8.