Postgresql存储过程返回表所有列

创建一个函数.该函数有一个输入参数.我可以返回一列,但我想返回所有表列.另外我想做的是如果结果为零,则函数返回0.我怎么能这样做？
这里是错误结果.

ERROR: query has no destination for result data
HINT: If you want to discard the results of a SELECT,use PERFORM instead.
CONTEXT: PL/pgsql function dwgCould.returnallcolumns(character varying) line 3 at sql statement
********** Error **********
ERROR: query has no destination for result data
sql state: 42601
Hint: If you want to discard the results of a SELECT,use PERFORM instead.
Context: PL/pgsql function dwgCould.returnallcolumns(character varying) line 3 at sql statement

CREATE OR REPLACE FUNCTION dwgCould.returnallcolumns(IN sessionId character varying)
  RETURNS SetoF public.mytable AS
$BODY$
BEGIN
    SELECT * FROM public.mytable WHERE session_id=returnallcolumns.sessionId ORDER BY pro_id DESC LIMIT 1;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;

如果要返回结果,则需要在PL / pgsql as documented in the manual中使用返回查询

CREATE OR REPLACE FUNCTION dwgCould.returnallcolumns(IN sessionId character varying)
  RETURNS SetoF public.mytable AS
$BODY$
BEGIN
  return query --<< this was missing
    SELECT * 
    FROM public.mytable 
    WHERE session_id = returnallcolumns.sessionId 
    ORDER BY pro_id DESC LIMIT 1;
END;
$BODY$
LANGUAGE plpgsql VOLATILE;

但是你不需要PL / pgsql,一个简单的sql函数会更有效：

CREATE OR REPLACE FUNCTION dwgCould.returnallcolumns(IN sessionId character varying)
  RETURNS SetoF public.mytable AS
$BODY$
    SELECT * 
    FROM public.mytable 
    WHERE session_id = returnallcolumns.sessionId 
    ORDER BY pro_id DESC LIMIT 1;
$BODY$
LANGUAGE sql;