Postgresql存儲過程返回表的所有列

Question

創建一個函數。該功能有一個輸入參數。我可以返回一列，但我想返回所有表列。如果結果爲零，我也想這樣做，函數只返回0.我該怎麼做？ 這裏的錯誤結果。

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

如果你想返回一個結果，你需要在PL/pgSQL的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; 

使用return query但你並不需要PL/pgSQL的這一點，一個簡單的SQL功能會更加高效：

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;