why does this works: let name = "'A 20'"
bd_rows <- query_ conn "select `N° BD` from sidonie.Coordonnées where Nom = 'A 20'"
The "Nom" equality constraint was the String: <A><SPACE><SPACE><SPACE><SPACE><2><0>
but not with this:
bd_rows <- query conn "select `N° BD` from sidonie.Coordonnées where Nom = ?" (Only (name::String))
No additional quoting is required or appropriate with prepared statements. The "Nom" constraint in this case was incorrectly: <'><A><SPACE><SPACE><SPACE><SPACE><2><0><'> This is not Haskell-specific. The fact that prepared statement parameters don't use or require quoting is an important safety feature (no SQL-injection with prepared statements). Every language that offers SQL bindings with prepared statement support behaves this way. -- Viktor.