更新语句到函数 PostgreSQL

Question

我有以下有效的代码：

UPDATE backup_factura 
    SET tipo = CASE 
                 WHEN total_fact <=100 THEN 'X'
                 WHEN total_fact <=200 THEN 'Y'
                 ELSE 'Z'
               END
RETURNING *;

我的老师让我把它转换成一个函数。我尝试了以下方法：

CREATE Function sp_test_case () returns void as $$ 
BEGIN

  UPDATE backup_factura 
    SET tipo = CASE 
                 WHEN total_fact <=100 THEN 'X'
                 WHEN total_fact <=200 THEN 'Y'
                 ELSE 'Z'
               END
  RETURNING *;

RETURN;   
END;   
$$ LANGUAGE plpgsql;

但是当我执行该函数时，我得到：

********** Error **********
ERROR: query has no destination for result data
SQL state: 42601
Context: PL / pgSQL sp_test_case () function in line 4 SQL statement

我也尝试过更复杂的方法：

CREATE Function sp_test_case () returns void as $$ 
DECLARE
    cont int=(Select MAX(id_fact)from backup_factura);
BEGIN

  while cont>0
  LOOP

    UPDATE backup_factura
    SET tipo= CASE 
            WHEN ((total_fact) <=100) THEN 'X'
            WHEN ((total_fact) <=200) THEN 'Y'
            ELSE 'Z'
           END;

    WHERE id_fact=cont;

    cont:=cont-1;

   END LOOP;

RETURN;   
END;   
$$ LANGUAGE plpgsql;

但我得到：

********** Error **********
ERROR: syntax error at or near "WHERE"
SQL state: 42601
Character: 283

关键是要显示这样的东西：

Answer 1

您可以使用 return query 语法和 return 一个 setof 您的 table:

CREATE Function sp_test_case () RETURNS SETOF backup_factura AS $$ 
BEGIN

  RETURN QUERY
  UPDATE backup_factura 
    SET tipo = CASE 
                 WHEN total_fact <=100 THEN 'X'
                 WHEN total_fact <=200 THEN 'Y'
                 ELSE 'Z'
               END
  RETURNING *;
END;   
$$ LANGUAGE plpgsql;

Answer 2

您可以像@Mureinik 发布的那样修复您的 plpgsql 函数。或者，更好的是，使用更简单的 SQL function:

CREATE FUNCTION sp_test_case ()
   RETURNS SETOF backup_factura AS
$func$
UPDATE backup_factura 
SET    tipo = CASE WHEN total_fact <= 100 THEN 'X'
                   WHEN total_fact <= 200 THEN 'Y'
                   ELSE 'Z' END
RETURNING *;
$func$ LANGUAGE sql;

致电：

SELECT * FROM sp_test_case();

更新语句到函数 PostgreSQL

UPDATE sentence to Function PostgreSQL

postgresql

stored-procedures

plpgsql