plpgsql语法错误在";"附近

Question

我看过这个类似的问题,但我认为我的问题可能有所不同.如果我正确理解他们的问题,问题是由上游的语法错误引起的.
在我的情况下,语法错误是如此接近程序的开头,它给了我一个可能出错的窗口,但是一切看起来都没问题.

码:

DO $$
DECLARE topic_cursor CURSOR FOR SELECT * FROM "socialMediaModel_topic" WHERE "active_search"=True;

BEGIN
OPEN topic_cursor;
FETCH FIRST FROM topic_cursor;
LOOP
    SELECT "topic" FROM topic_cursor AS "c_topic";
    SELECT "topic_id" FROM topic_cursor AS "c_id";
    SELECT "active_search" FROM topic_cursor AS "c_active";

    INSERT INTO "socialMediaModel_datacollection" ("name", "active")
        VALUES (c_topic, c_active);
    INSERT INTO "socialMediaModel_datacollectiontopic" ("data_collection_id_id", "topic_id_id")
        VALUES ((SELECT "data_collection_id" FROM "DataCollection" where name=c_topic), c_id);

    FETCH NEXT FROM topic_cursor;

END LOOP;
CLOSE topic_cursor;

UPDATE "socialMediaModel_topic" SET "active_search" = False WHERE "active_search"=True;
COMMIT;
END$$;

错误:

ERROR:  syntax error at or near ";"
LINE 9:  FETCH FIRST FROM topic_cursor;
                                  ^
********** Error **********

ERROR: syntax error at or near ";"
SQL state: 42601
Character: 247

在编写此脚本时,我几乎完全遵循这些资源:

• PostgreSQL文档:游标
• PostgreSQL文档:DO

数据库:PostgreSQL 9.1
编辑器:pgAdmin III查询工具

如果我错过了一些非常明显的事情,我会提前道歉.我一整天都在盯着这个剧本,所以我的大脑可能会有点乱.

Answer 1

程序解决方案

您的代码中存在许多问题.
这应该工作,也更快:

DO
$do$
DECLARE
   rec record;
BEGIN
   FOR rec IN
      SELECT s.*, d.data_collection_id
      FROM   "socialMediaModel_topic" s
      LEFT   JOIN "DataCollection"    d ON d.name = s.topic
      WHERE  active_search
   LOOP
      INSERT INTO "socialMediaModel_datacollection" (name, active)
      VALUES (rec.topic, rec.active_search);
      INSERT INTO "socialMediaModel_datacollectiontopic"
                              (data_collection_id_id, topic_id_id)
      VALUES (rec.data_collection_id, rec.topic_id);
   END LOOP;

   UPDATE "socialMediaModel_topic"
   SET    active_search = FALSE
   WHERE  active_search;
END
$do$;

主要观点

• FETCH语法不正确.

• 有没有COMMIT在一个DO声明.整个事情在一个事务中自动运行,就像一个函数.

• 你没有条件终止你的循环.

• 几乎没有必要使用显式游标.使用更方便(通常更快)的FOR循环隐式游标.

• 我会建议反对Postgres中的CaMeL案例标识符.仅使用合法的小写标识符.

基于集合的解决方案

的整个程序的方法是低劣到与基于集合的方法修改数据的CTE的:

WITH ins1 AS (
   INSERT INTO "socialMediaModel_datacollection" (name, active)
   SELECT topic, active_search
   FROM   "socialMediaModel_topic"
   WHERE  active_search
   )
, ins2 AS (
   INSERT INTO "socialMediaModel_datacollectiontopic"
                           (data_collection_id_id, topic_id_id)
   SELECT d.data_collection_id, s.topic_id
   FROM   "socialMediaModel_topic" s
   LEFT   JOIN "DataCollection"    d ON d.name = s.topic
   WHERE  s.active_search
   )
UPDATE "socialMediaModel_topic"
SET    active_search = FALSE
WHERE  active_search;

或者,如果您有并发写入负载,请使用FOR UPDATE以避免竞争条件:

WITH sel AS (
   SELECT s.topic_id, s.topic, s.active_search, d.data_collection_id
   FROM   "socialMediaModel_topic" s
   LEFT   JOIN "DataCollection"    d ON d.name = s.topic
   WHERE  s.active_search
   FOR    UPDATE
   )
, ins1 AS (
   INSERT INTO "socialMediaModel_datacollection" (name, active)
   SELECT topic, active_search FROM sel
   )
, ins2 AS (
   INSERT INTO "socialMediaModel_datacollectiontopic"
                           (data_collection_id_id, topic_id_id)
   SELECT d.data_collection_id, s.topic_id FROM sel
   )
UPDATE "socialMediaModel_topic"
SET    active_search = FALSE
WHERE  active_search;

有关SELECT ... FOR UPDATECTE的更多信息:
我应该在事务中包含SELECT吗？

类似的问题/答案:
如何在PostgreSQL中使用游标提高函数的性能？