Question

Trying to get into PostgreSQL.
I’m drawing an function that will check credentials

Here is it:

CREATE or REPLACE  FUNCTION CkeckUser (Login varchar(50), Password varchar(50)) 
RETURNS TABLE(ID int, IDParent int, Text varchar(50), Image bytea, DLLName varchar(50), MethodName varchar(50), Parameters varchar(250) )
 AS $$
DECLARE
  idu INT;
BEGIN

idu := null;

 select idu = u."ID"
 FROM  "Users" u
 where (u."Login" = $1) and (u."Password" = $2);

  select 
utm."IDMenuItem" as ID,
utm."IDParentMenuItem" as IDParent,
m."Text",
m."Image",
m."DLLName",
m."MethodName",
m."Parameters"
    from        "Users" u
            join "UserTypes" ut on u."Type" = ut."ID"
            join "UserTypeMenu" utm on u."Type" = utm."IDUserType"
            join "Menu" m on utm."IDMenuItem" = m."ID";
where u."ID" = IDU;
order by m."ID";

END; $$
 LANGUAGE 'plpgsql';

Logics is pretty simple but on executing it

 select CkeckUser(N'admin', N'test');

or

  select * from CkeckUser(N'admin', N'test');

I got

  ERROR:  query has no destination for result data

where I’m wrong?

Answer 1

In PL/pgSQL, you can’t just run a query; you have to put the results somewhere. I take it that you want the function to return the query result?

You can put RETURN QUERY before the query, which will append its result-set to the function’s return-value, but in your case, if that’s the entirety of your stored procedure, it’s probably easier to just change your stored-procedure to be pure SQL rather than PL/pgSQL:

CREATE or REPLACE FUNCTION CkeckUser (Login varchar(50), Password varchar(50)) 
RETURNS TABLE(ID int, IDParent int, Text varchar(50), Image bytea, DLLName varchar(50), MethodName varchar(50), Parameters varchar(250) )
  AS
  $$
    SELECT utm."IDMenuItem" AS ID,
           utm."IDParentMenuItem" as IDParent,
           m."Text",
           m."Image",
           m."DLLName",
           m."MethodName",
           m."Parameters"
      FROM "Users" u
      JOIN "UserTypes" ut
        ON u."Type" = ut."ID"
      JOIN "UserTypeMenu" utm
        ON u."Type" = utm."IDUserType"
      JOIN "Menu" m
        ON utm."IDMenuItem" = m."ID"
     WHERE u."ID" = ( SELECT u."ID"
                        FROM "Users" u
                       WHERE u."Login" = $1
                         AND u."Password" = $2
                    )
     ORDER
        BY m."ID"
  $$
  LANGUAGE 'SQL'
;