Postgres FOR LOOP 的语法错误答案

【问题标题】：Syntax error with Postgres FOR LOOPPostgres FOR LOOP 的语法错误
【发布时间】：2010-05-15 08:33:16
【问题描述】：

我的 postgres 函数有问题：

CREATE OR REPLACE FUNCTION linkedRepoObjects(id bigint) 
        RETURNS int  AS $$ 
          DECLARE catNumber int DEFAULT 0;
          DECLARE cat RECORD;
        BEGIN
        WITH RECURSIVE children(categoryid,category_fk) AS (
         SELECT categoryid, category_fk
         FROM b2m.category_tab 
         WHERE categoryid = 1
           UNION ALL
         SELECT c1.categoryid,c1.category_fk
         FROM b2m.category_tab c1, children 
         WHERE children.categoryid = c1.category_fk
         )


    FOR cat IN SELECT * FROM children LOOP
      IF EXISTS (SELECT 1 FROM b2m.repoobject_tab WHERE category_fk = cat.categoryid)   THEN
            catNumber = catNumber +1
      END IF;
    END LOOP;

         RETURN catNumber;

         END;
    $$ LANGUAGE 'plpgsql';

我有错误：

FEHLER:  Syntax error near »FOR«
LINE 1: ...dren WHERE children.categoryid = c1.category_fk ) FOR  $2  I...

【问题讨论】：

标签： postgresql stored-procedures for-loop plpgsql

【解决方案1】：

语法错误是因为它期望WITH ... 后面跟着SELECT，它在哪里找到FOR。

我没有在 plpgsql 的查询中使用 WITH 子句，但我会尝试将 FOR cat IN 移动到 WITH 之前，这是查询的一部分。

【讨论】：

【解决方案2】：

试试这个：

CREATE OR REPLACE FUNCTION linkedRepoObjects(id bigint) RETURNS int AS 
$$ 
DECLARE catNumber int DEFAULT 0;
DECLARE cat RECORD;
BEGIN

    FOR cat IN    

        WITH RECURSIVE children(categoryid,category_fk) AS (
        SELECT categoryid, category_fk
        FROM b2m.category_tab 
        WHERE categoryid = 1
        UNION ALL
        SELECT c1.categoryid,c1.category_fk
        FROM b2m.category_tab c1, children 
        WHERE children.categoryid = c1.category_fk
        )
        SELECT * FROM children 

    LOOP

        IF EXISTS (SELECT 1 FROM b2m.repoobject_tab WHERE category_fk = cat.categoryid)   THEN
            catNumber = catNumber +1
        END IF;

    END LOOP;

    RETURN catNumber;

END;
$$ LANGUAGE 'plpgsql';

我注意到您的查询几乎不需要循环，只需这样做：

CREATE OR REPLACE FUNCTION linkedRepoObjects(id bigint) RETURNS int AS 
$$ 
BEGIN

    RETURN
    (  
    SELECT COUNT(*) FROM b2m.repoobject_tab WHERE category_fk IN 
        (
            WITH RECURSIVE children(categoryid,category_fk) AS 
            (
                SELECT categoryid, category_fk
                FROM b2m.category_tab 
                WHERE categoryid = 1
                UNION ALL
                SELECT c1.categoryid,c1.category_fk
                FROM b2m.category_tab c1, children 
                WHERE children.categoryid = c1.category_fk
            )
            SELECT categoryid FROM children 
        )
     );
END;
$$ LANGUAGE 'plpgsql';

【讨论】：

确实，我刚刚习惯了 plpgsql :-)