... thx all for helping. Now the coding works: it puts the following out.
Kind regards
Hartmut
*Main> main
Only {fromOnly = 4}
------------------------------
Only {fromOnly = 101}
Only {fromOnly = 102}
Only {fromOnly = 103}
------------------------------
blub 101 51
blub 102 52
blub 103 53
The Coding is:
-- PostgreSQL-Simple test
{-# LANGUAGE OverloadedStrings #-}
import Database.PostgreSQL.Simple
import Data.Foldable
import qualified Data.Text as Text
myconn :: ConnectInfo
myconn = defaultConnectInfo {
connectUser = "test",
connectPassword = "test",
connectDatabase = "test"}
db_calc :: (FromRow a) => IO [a]
db_calc = do
conn <- connect myconn
query_ conn "select 2 + 2"
hr :: IO ()
hr = putStrLn "------------------------------"
main :: IO ()
main = do
conn <- connect myconn
-- Let Database calculate 2+2
x1 <- db_calc
forM_ x1 $ \h ->
putStrLn $ show (h :: Only Int)
-- Select single integer column
hr; x2 <- query_ conn "select aaa from aaa"
forM_ x2 $ \(col1) ->
putStrLn $ show (col1 :: Only Int)
-- select integer and text columns together
hr; x3 <- query_ conn "select aaa,bbb,textcol from aaa"
forM_ x3 $ \(int_col_1,int_col_2,text_col_3) ->
putStrLn $
Text.unpack text_col_3 ++ " "
++ show (int_col_1 :: Int) ++ " "
++ show (int_col_2 :: Int)
return ()
On 08/18/2013 12:12 AM, Brandon Allbery wrote:
On Sat, Aug 17, 2013 at 5:59 PM, Hartmut Pfarr
<hartmut0...@googlemail.com <mailto:hartmut0...@googlemail.com>> wrote:
query_ conn "select 2 + 2"
I've no errors any more.
But: I don't see any result (for sure, it is not coeded yet)
Yes, because you're not capturing it; it's the return value from
`query_`, which you are throwing away above instead of capturing with
some kind of `res <- query_ ...`. Again, see that section of the
documentation I pointed to for how to get results.
--
brandon s allbery kf8nh sine nomine associates
allber...@gmail.com <mailto:allber...@gmail.com> ballb...@sinenomine.net
<mailto:ballb...@sinenomine.net>
unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net
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