触发器中的 "NEW" table 有时包含列，有时不包含

Question

我一直在尝试创建一个 INSERT 触发器，在一个简单的触发器主体中，我可以访问“NEW”table 就好了。

但是在一个示例中，“新”table 用于更深的主体，它不再找到我需要的列。

我可以在以下位置找到列“NEW.nr_legitimatie”：

CREATE DEFINER=`root`@`localhost` 
TRIGGER `calculMedie` 
AFTER INSERT ON `note` 
FOR EACH ROW 
INSERT INTO medii (MEDII.nr_legitimatie, MEDII.medie_generala, medii.medie_an1, medii.medie_an2, medii.medie_an3)
VALUES (new.nr_legitimatie, 1, 2, 3, 4)

我在以下位置找不到列“NEW.nr_legitimatie”：

CREATE DEFINER=`root`@`localhost` 
TRIGGER `calculMedie` 
AFTER INSERT ON `note` 
FOR EACH ROW 
INSERT INTO medii (MEDII.nr_legitimatie, MEDII.medie_generala, medii.medie_an1, medii.medie_an2, medii.medie_an3)
WITH date AS (
    WITH medii_pe_coloane AS (
        SELECT medie1.nr_legitimatie, 
            AVG(medie1.maxim) as medie_an_1, 
            AVG(medie2.maxim) as medie_an_2, 
            AVG(medie3.maxim) as medie_an_3
        FROM 
        (
        SELECT nr_legitimatie, disciplina, an_studiu, MAX(nota) AS maxim 
        FROM note 
        WHERE an_studiu = 1 AND nr_legitimatie = new.nr_legitimatie
        GROUP BY nr_legitimatie, disciplina
        ) as medie1,
        (
        SELECT nr_legitimatie, disciplina, an_studiu, MAX(nota) AS maxim 
        FROM note 
        WHERE an_studiu = 2 AND nr_legitimatie = new.nr_legitimatie
        GROUP BY nr_legitimatie, disciplina
        ) as medie2,
        (
        SELECT nr_legitimatie, disciplina, an_studiu, MAX(nota) AS maxim 
        FROM note 
        WHERE an_studiu = 3 AND nr_legitimatie = new.nr_legitimatie
        GROUP BY nr_legitimatie, disciplina
        ) as medie3
    ),
    medii_union AS (
        SELECT medii_pe_coloane.medie_an_1 as medie from medii_pe_coloane
        UNION ALL
        SELECT medii_pe_coloane.medie_an_2 as medie from medii_pe_coloane
        UNION ALL
        SELECT medii_pe_coloane.medie_an_3 as medie from medii_pe_coloane
    ),
    medie_generala AS (
        SELECT AVG(medii_union.medie) as medie FROM medii_union
    )
        
    
    SELECT medii_pe_coloane.*, medie_generala.medie from medii_pe_coloane, medie_generala
)
SELECT nr_legitimatie, medie, medie_an_1, medie_an_2, medie_an_3
FROM date

我无法理解可能发生的事情。它没有被覆盖。也许它超出了它的范围？我怎么可能在 WHERE 子句中使用它？

错误是：

#1054 - Unknown column 'nr_legitimatie' in 'NEW'

为了测试它，我在 note table 中插入了一个新行，其中 100% 包含“nr_legitimatie”列。

MariaDB 10.4

Answer 1

我在 phone 所以还没有测试过这个，但也许你不能在同一个触发器中引用 NEW 三次？

如果是这样，我会重写您的查询，无论如何它看起来都有逻辑错误。

这是我建议的查询...

INSERT INTO
  medii (
    MEDII.nr_legitimatie, MEDII.medie_generala, medii.medie_an1, medii.medie_an2, medii.medie_an3
  )
WITH
  max_an_studiu AS
(
    SELECT nr_legitimatie, disciplina, an_studiu, MAX(nota) AS maxim 
      FROM note 
     WHERE an_studiu IN (1, 2, 3)
       AND nr_legitimatie = (SELECT nr_legitimatie FROM new)
  GROUP BY nr_legitimatie, disciplina, an_studiu
),
  medie AS
(
  SELECT
    nr_legitimatie,
    an_studiu,
    AVG(maxim) AS medie
  FROM
    max_an_studiu
  GROUP BY
    nr_legitimatie,
    an_studiu
)
SELECT
  nr_legitimatie,
  AVG(medie)                                AS medie,
  MAX(CASE WHEN an_studiu=1 THEN medie END) AS medie_an_1,
  MAX(CASE WHEN an_studiu=2 THEN medie END) AS medie_an_2,
  MAX(CASE WHEN an_studiu=3 THEN medie END) AS medie_an_3
FROM
  medie
GROUP BY
  nr_legitimatie

Answer 2

这是一个 MariaDB bug (see especially this comment 具有接近您的问题的可重现示例）带有误导性错误消息。

当您重用使用 new 的 CTE 时，您的错误发生在触发器中。

在您的情况下，您在 medii_union 中使用了 medii_pe_coloane（即使用 new）3 次，在 date 的最后 select 中使用了一次.这会触发错误。

不过，您可以随意使用 new 本身（在任意多的 CTE 中）。所以解决方法是多次重新定义 CTE，例如像

WITH medii_pe_coloane AS ( <query using "new"> ),
     medii_pe_coloane1 AS ( <same query using "new"> ),
     medii_pe_coloane2 AS ( <same query using "new"> ),
     medii_pe_coloane3 AS ( <same query using "new"> ),
...
medii_union AS (
           select medii_pe_coloane1.medie_an_1 ... from medii_pe_coloane1 
 union all select medii_pe_coloane2.medie_an_2 ... from medii_pe_coloane2
 union all select medii_pe_coloane3.medie_an_3 ... from medii_pe_coloane3)
... 
SELECT ... from medii_pe_coloane, medie_generala

使您的代码有点重复，但应该作为一般解决方法使用。或者，您可以重写 and/or 以其他方式简化您的查询（参见）。

触发器中的 "NEW" table 有时包含列，有时不包含

The "NEW" table in a trigger sometimes contains column and sometimes it does not

mysql

sql

phpmyadmin

mariadb-10.4