不能在 MARIADB 的删除语句中使用 ALIAS

Question

我正在尝试从 table 中删除重复项，但它不允许我使用别名。尝试了以多种形式给出的各种解决方案。

查询是，

DELETE FROM `table` AS t1
        WHERE EXISTS (
         SELECT 1 FROM `table` AS t2
         WHERE t2.`col1` = t1.`col1`
         AND t2.`col2` = t1.`col2`
         AND t2.id > t1.id )

Answer 1

您可以尝试使用内部联接而不是存在子查询

DELETE t
FROM `billing_squarecustomer` t
INNER JOIN  (
   SELECT  t2.`patient_id`.
   FROM `billing_squarecustomer` AS t2
   INNER JOIN `billing_squarecustomer` AS t1
   WHERE t2.`patient_id` = t1.`patient_id`
   AND t2.`merchant_id` = t1.`merchant_id`
   AND t2.id > t1.id
) tdel = tdel.patient_id = t.patient_id

Answer 2

可以使用多tableDELETE语句：

DELETE t1 
FROM `table` t1
JOIN `table` t2 ON t2.col1 = t1.col1 AND t2.col2 = t1.col2 AND t2.id > t1.id

Answer 3

当 id 为 primary key

时，您可以使用 left join 删除同一个 table 中的重复项

delete t1
from `table` as t1
left join `table` as t2 on t1.col1 = t2.col1 and t1.col2 = t2.col2 and t1.id < t2.id
where t2.id is not null;

Answer 4

你可以试试这个，它更复杂但到目前为止更安全，因为使用 inner inside delete 可能真的很危险，这样你可以先检查你要删除的内容：

SET @discriminator = 0;
SET @p1 = null;
SET @p2 = null;

CREATE TEMPORARY TABLE temp_rows(
    `id` INT PRIMARY KEY,
    `index` INT,
    `col1` COL1TYPE,
    `col2` COL2TYPE
);

INSERT INTO temp_rows (`index`, `col1`, `col2`, `id`)
SELECT CASE WHEN @p1 != col1 OR @p2 != col2 THEN @discriminator := 0 ELSE @discriminator := @discriminator + 1 END AS 'index', 
    @p1 := col1 AS 'col1', 
    @p2 := col2 AS 'col2',
    id
FROM `schema`.table
ORDER BY col1, col2, id desc;

DELETE FROM table WHERE EXISTS (
     SELECT 1 FROM `temp_rows`
     WHERE table.`id` = temp_rows.`id`
);

DROP TEMPORARY TABLE temp_rows;

不能在 MARIADB 的删除语句中使用 ALIAS

Can't use ALIAS in delete statement in MARIA DB

mysql

mariadb

mariasql