haskelldb-2.2.1: A library of combinators for generating and executing SQL statements.

Safe HaskellNone



Defines the types of database columns, and functions for converting these between HSQL and internal formats



type FieldDesc = (FieldType, Bool)Source

The type and nullable flag of a database column

data FieldType Source

A database column type


Eq FieldType 
Ord FieldType 
Read FieldType 
Show FieldType 

class ExprType e whereSource

Class which retrieves a field description from a given type. Instances are provided for most concrete types. Instances for Maybe automatically make the field nullable, and instances for all (Expr a) types where a has an ExprType instance allows type information to be recovered from a given column expression.


class ExprTypes r whereSource

Class which returns a list of field descriptions. Gets the descriptions of all columns in a Record/query. Most useful when the columns associated with each field in a (Rel r) type must be recovered. Note that this occurs at the type level only and no values are inspected.

queryFields :: (ShowLabels r, ExprTypes r) => Query (Rel r) -> [(String, FieldDesc)]Source

Given a query, returns a list of the field names and their types used by the query. Useful for recovering field information once a query has been built up.