How convert '<unnamed portal 1>' to dataset of a plpgsql function in VB.NET

Question

I was learning some basics of PostgreSQL basics. while i am trying to return a resutset from PostgreSQL stored function to a VB.NET application i stuck with the following scenarios

##--- my PostgreSQL function is

 CREATE OR REPLACE FUNCTION checkLogin( IN p_uname TEXT,IN p_pwd TEXT) RETURNS refCursor AS $BODY$ DECLARE ref refCursor; BEGIN OPEN ref FOR SELECT UserMaster.* FROM UserMaster WHERE username=p_uname AND userpwd=p_pwd AND coalesce(userdel,FALSE)=FALSE; RETUR ref; END; $BODY$ LANGUAGE PLPGSQL 

-- My VB function To return dataset is following

 Function CheckLogin(ByVal username As String,ByVal pwd As String) As DataSet Try Dim ds As New DataSet Dim conString As String="Server=localhost;port=5432;Database=myDB;UserId=postgres;password=postgres" Dim con As NpgsqlConnection=New NpgsqlConnection(ConString) con.open() Dim com As NpgsqlCommand=New NpgsqlCommand("select * from checkLogin('"+ username +"','"+ pwd +"')",con) Dim da As NpgsqlDataAdapter=New NpgsqlDataAdapter(com) da.Fill(ds) Return ds Catch ex As Exception Return Nothing End Try End Function 

From this function it just return 'unnamed portal 1' within a tag my question is how can i convert it into DataSet. its really helpful if anybody answer it and mention what i do wrong. I googled and read most of the article related with this. But i didn't find a proper solution for this. if there is a link please mention it to me and excuse me for this question.

thanks in advance

Answer 1

If what you want is a function that returns a set of rows (much like a table), then your function should probably return a table (see the docs , or this question for an example) instead of a refcursor.

A refcursor is a server-side object which allows you to retrieve the query results in special ways (eg fetching a certain number of rows at a time, resetting it). If your function returns a refcursor you will need to interact with it by sending further queries as described in the docs . It doesn't seem like your use-case warrants this complexity.

Answer 2

I changed my stored function like following

CREATE OR REPLACE FUNCTION checkLogin(
IN p_uname TEXT,IN p_pwd TEXT) RETURNS TABLE(uid INTEGER,uname CHARACTOR varying,utype integer) AS
$BODY$

    BEGIN 
        RETURN QUERY
        SELECT userId,userName,userType FROM UserMaster WHERE username=p_uname AND userpwd=p_pwd AND coalesce(userdel,FALSE)=FALSE;

    END;
$BODY$
LANGUAGE PLPGSQL

this pgSQL function works fine and returns resultset and can to convert it to dataset easily.