postgresql - PL/pgSQL 函数中的 SELECT 或 PERFORM

Question

我的数据库中有这个函数:

CREATE OR REPLACE FUNCTION "insertarNuevoArticulo"(nombrearticulo character varying, descripcion text, idtipo integer, idfamilia bigint, artstock integer, minstock integer, maxstock integer, idmarca bigint, precio real, marcastock integer)
RETURNS boolean AS
$BODY$
DECLARE
    articulo "Articulo"%ROWTYPE;
BEGIN
    SELECT * INTO articulo FROM "Articulo" WHERE "Nombre" = $1 AND "idTipo"=$3 AND "idFamilia"=$4;
    IF NOT FOUND THEN
        INSERT INTO "Articulo" ("Nombre", "Descripcion", "idTipo", "idFamilia", "Stock", "MinStock", "MaxStock") Values ($1, $2, $3, $4, $5, $6, $7);
        SELECT last_value
        INTO articulo."idArticulo"
        FROM "public"."Articulo_idArticulo_seq";
    END IF;
    SELECT * FROM "ArticuloMarca" AS am WHERE am."idArticulo" = articulo."idArticulo" and am."idMarca" = $8;
    IF NOT FOUND THEN
        Insert into "ArticuloMarca"("idArticulo", "idMarca", "PrecioReferencial", "Stock") Values (articulo."idArticulo", $8, $9, $10);
        RETURN TRUE;
    END IF;
    RETURN FALSE;
END;
$BODY$
 LANGUAGE plpgsql VOLATILE
 COST 100;
 ALTER FUNCTION "insertarNuevoArticulo"(character varying, text, integer, bigint, integer, integer, integer, bigint, real, integer)
 OWNER TO postgres;

但是当我尝试使用它时，它说如果我想丢弃结果，我需要使用 PERFORM!这里的问题是我不想!我希望它们位于我声明的 articulo 行中!

我正在使用这个语句:

SELECT "insertarNuevoArticulo"('Acetaminofen', 'caro', '1' , '1', '8', '1', '10', '1', '150.7', '10');

我得到的错误是 42601，一个语法错误!如果我用IDE创建它会怎样？对这个问题有什么想法吗？

Answer 1

在 plpgsql 代码中，没有目标的 SELECT 会触发错误。但是您显然不想要SELECT INTO，您只想设置FOUND 的状态。你会使用 PERFORM为此。

• SELECT raises exception in PL/pgSQL function

更好的是，使用IF EXISTS ...。考虑重写您的函数:

CREATE OR REPLACE FUNCTION "insertarNuevoArticulo"( nombrearticulo text, descripcion text, idtipo int, idfamilia bigint, artstock int, minstock int, maxstock int, idmarca bigint, precio real, marcastock int)
  RETURNS boolean
  LANGUAGE plpgsql AS
$func$
DECLARE
    _id_articulo "Articulo"."idArticulo"%TYPE;
BEGIN
    SELECT a."idArticulo" INTO _id_articulo
    FROM   "Articulo" a
    WHERE  a."Nombre" = $1 AND a."idTipo" = $3 AND a."idFamilia" = $4;

    IF NOT FOUND THEN
        INSERT INTO "Articulo"("Nombre", "Descripcion", "idTipo", "idFamilia", "Stock", "MinStock", "MaxStock")
        VALUES ($1, $2, $3, $4, $5, $6, $7)
        RETURNING "Articulo"."idArticulo" INTO _id_articulo;
    END IF;

   IF EXISTS (SELECT FROM "ArticuloMarca" a
              WHERE a."idArticulo" = _id_articulo AND a."idMarca" = $8) THEN
      RETURN false;
   ELSE
      INSERT INTO "ArticuloMarca"("idArticulo", "idMarca", "PrecioReferencial", "Stock")
      VALUES (_id_articulo, $8, $9, $10);
      RETURN true;
    END IF;
END
$func$;

关于 EXISTS:

• PL/pgSQL checking if a row exists

其他要点:

• 使用RETURNING clause INSERT 语句，而不是额外的 SELECT。

Postgres 9.5+

在 Postgres 9.5 或更高版本中，使用 INSERT ... ON CONFLICT DO NOTHING(也称为“UPSERT”)。
您将对 "Articulo"("Nombre", "idTipo", "idFamilia") 和 "ArticuloMarca"("idArticulo", "idMarca"") 然后:

CREATE OR REPLACE FUNCTION insert_new_articulo( nombrearticulo text, descripcion text, idtipo int, idfamilia bigint, artstock int, minstock int, maxstock int, idmarca bigint, precio real, marcastock int)
  RETURNS boolean
  LANGUAGE plpgsql AS
$func$
DECLARE
    _id_articulo "Articulo"."idArticulo"%TYPE;
BEGIN
   LOOP
      SELECT "idArticulo" INTO _id_articulo
      FROM   "Articulo"
      WHERE  "Nombre" = $1 AND "idTipo" = $3 AND "idFamilia" = $4;

      EXIT WHEN FOUND;

      INSERT INTO "Articulo"("Nombre", "Descripcion", "idTipo", "idFamilia", "Stock", "MinStock", "MaxStock")
      VALUES ($1, $2, $3, $4, $5, $6, $7)
      ON     CONFLICT (tag) DO NOTHING
      RETURNING "idArticulo" INTO _id_articulo;

      EXIT WHEN FOUND;
   END LOOP;

   LOOP
      INSERT INTO "ArticuloMarca"("idArticulo", "idMarca", "PrecioReferencial", "Stock")
      VALUES (_id_articulo, $8, $9, $10)
      ON     CONFLICT ("idArticulo", "idMarca") DO NOTHING;

      IF FOUND THEN
         RETURN true;
      END IF;

      IF EXISTS (SELECT FROM "ArticuloMarca"
                 WHERE "idArticulo" = _id_articulo AND "idMarca" = $8) THEN
         RETURN false;
      END IF;
   END LOOP;
END
$func$;

这样更快、更简单、更可靠。添加的循环排除了并发写入的任何剩余竞争条件(同时几乎不增加任何成本)。没有并发写入，你可以简化。详细解释:

• Is SELECT or INSERT in a function prone to race conditions?
• How to use RETURNING with ON CONFLICT in PostgreSQL?

另外:使用合法的小写标识符来避免所有嘈杂的double-quotes .