query package:postgresql-simple

query :: (ToRow q, FromRow r) => Connection -> Query -> q -> IO [r]

postgresql-simple Database.PostgreSQL.Simple

Perform a SELECT or other SQL query that is expected to return results. All results are retrieved and converted before this function returns. When processing large results, this function will consume a lot of client-side memory. Consider using fold instead. Exceptions that may be thrown:

FormatError: the query string could not be formatted correctly.
QueryError: the result contains no columns (i.e. you should be using execute instead of query).
ResultError: result conversion failed.
SqlError: the postgresql backend returned an error, e.g. a syntax or type error, or an incorrect table or column name.

query :: (ToRow q, FromRow r) => Connection -> Query -> q -> IO (Vector r)

postgresql-simple Database.PostgreSQL.Simple.Vector

Perform a SELECT or other SQL query that is expected to return results. All results are retrieved and converted before this function returns.

query :: (ToRow q, FromRow r, Unbox r) => Connection -> Query -> q -> IO (Vector r)

postgresql-simple Database.PostgreSQL.Simple.Vector.Unboxed

Perform a SELECT or other SQL query that is expected to return results. All results are retrieved and converted before this function returns.

data Query

postgresql-simple Database.PostgreSQL.Simple

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.PostgreSQL.Simple

q :: Query
q = "select ?"

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

newtype Query

postgresql-simple Database.PostgreSQL.Simple.Types

{-# LANGUAGE OverloadedStrings #-}

import Database.PostgreSQL.Simple

q :: Query
q = "select ?"

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

Query :: ByteString -> Query

postgresql-simple Database.PostgreSQL.Simple.Types

queryWith :: ToRow q => RowParser r -> Connection -> Query -> q -> IO [r]

postgresql-simple Database.PostgreSQL.Simple

A version of query taking parser as argument

queryWith_ :: RowParser r -> Connection -> Query -> IO [r]

postgresql-simple Database.PostgreSQL.Simple

A version of query_ taking parser as argument

query_ :: FromRow r => Connection -> Query -> IO [r]

postgresql-simple Database.PostgreSQL.Simple

A version of query that does not perform query substitution.

queryWith :: ToRow q => RowParser r -> Connection -> Query -> q -> IO (Vector r)

postgresql-simple Database.PostgreSQL.Simple.Vector

A version of query taking parser as argument

queryWith_ :: RowParser r -> Connection -> Query -> IO (Vector r)

postgresql-simple Database.PostgreSQL.Simple.Vector

A version of query_ taking parser as argument

query_ :: FromRow r => Connection -> Query -> IO (Vector r)

postgresql-simple Database.PostgreSQL.Simple.Vector

A version of query that does not perform query substitution.

queryWith :: (ToRow q, Unbox r) => RowParser r -> Connection -> Query -> q -> IO (Vector r)

postgresql-simple Database.PostgreSQL.Simple.Vector.Unboxed

A version of query taking parser as argument

queryWith_ :: Unbox r => RowParser r -> Connection -> Query -> IO (Vector r)

postgresql-simple Database.PostgreSQL.Simple.Vector.Unboxed

A version of query_ taking parser as argument

query_ :: (FromRow r, Unbox r) => Connection -> Query -> IO (Vector r)

postgresql-simple Database.PostgreSQL.Simple.Vector.Unboxed

A version of query that does not perform query substitution.

data QueryError

postgresql-simple Database.PostgreSQL.Simple Database.PostgreSQL.Simple.Internal

Exception thrown if query is used to perform an INSERT-like operation, or execute is used to perform a SELECT-like operation.

QueryError :: String -> Query -> QueryError

postgresql-simple Database.PostgreSQL.Simple Database.PostgreSQL.Simple.Internal

EmptyQuery :: ExecStatus

postgresql-simple Database.PostgreSQL.Simple

The string sent to the server was empty.

fmtQuery :: FormatError -> Query

postgresql-simple Database.PostgreSQL.Simple Database.PostgreSQL.Simple.Internal

formatQuery :: ToRow q => Connection -> Query -> q -> IO ByteString

postgresql-simple Database.PostgreSQL.Simple

Format a query string. This function is exposed to help with debugging and logging. Do not use it to prepare queries for execution. String parameters are escaped according to the character set in use on the Connection. Throws FormatError if the query string could not be formatted correctly.

qeQuery :: QueryError -> Query

postgresql-simple Database.PostgreSQL.Simple Database.PostgreSQL.Simple.Internal

fromQuery :: Query -> ByteString

postgresql-simple Database.PostgreSQL.Simple.Types