Postgresql存储过程返回表所有列

Question

创建了一个函数。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。如果结果为零，我也想做，函数只返回 0。我该怎么做？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;

Answer 1

如果要返回一个结果，需要在PL/pgSQL中使用return query as documented in the manual

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;