MariaDB 10.1 中 DELETE 语法错误的未知原因

Question

on db Fiddle 下面的代码在 MariaDB 10.1 上运行时给出：

错误：

您的 SQL 语法有错误；检查手册 对应于您的 MariaDB 服务器版本，以便使用正确的语法 'DELETE pm FROM wp_postmeta pm WHERE post_id IN (SELECT post_id ' 在第 26 行

查询：

-- Block 1: Deleting all duplicate products in wp_posts table 
DELETE FROM wp_posts 
WHERE  id IN (SELECT id 
              FROM   (SELECT id, 
                             post_title, 
                             post_type, 
                             meta_value 
                      FROM   (SELECT wp_posts.id, 
                                     wp_postmeta.post_id, 
                                     post_title, 
                                     post_type, 
                                     meta_value, 
                                     Row_number() 
                                       OVER( 
                                         partition BY post_title 
                                         ORDER BY wp_postmeta.meta_value) rn 
                              FROM   wp_postmeta 
                                     JOIN wp_posts 
                                       ON wp_postmeta.post_id = wp_posts.id 
                              WHERE  wp_posts.post_type = 'Product' 
                                     AND wp_postmeta.meta_key = '_regular_price' 
                             ) t 
                      WHERE  t.rn <> 1) AS aliasx); 

-- Block 2: Deleting all corresponding wp_postmeta.post_ids that don't have a match in wp_posts.id after the duplicate deletion above
DELETE pm 
FROM   wp_postmeta pm 
WHERE  post_id IN (SELECT post_id 
                   FROM  (SELECT post_id 
                          FROM   wp_postmeta pm 
                                 LEFT JOIN wp_posts p 
                                        ON p.id = pm.post_id 
                          WHERE  p.id IS NULL 
                                 AND p.post_type = "product") i) 

如何纠正这个错误？我注意到第一个和第二个代码块单独输入时不会出现错误，但是一起输入时会出现此错误...

Answer 1

WordPress 使用的 MySQL API 不允许您将两个串联查询（在您的情况下为两个 DELETE）作为一个查询。 dbfiddle 也没有。分别运行查询。

如果您习惯于其他表服务器，这可能会让人感到困惑。

Answer 2

它实际上只是拆分 Delete 语句

create table wp_posts (
  ID integer primary key auto_increment,
  post_title varchar(30),
  post_type varchar(30)
);

✓

create table wp_postmeta (
  ID integer primary key auto_increment,
  post_id integer,
  meta_key varchar(30) not null default '_regular_price',
  meta_value integer not null
);

✓

insert into wp_posts (post_title, post_type) values
('Apple Pie','Product'),
('French Toast','Product'),
('Shepards Pie','Product'),
('Jam Pie','Product'),
('Jam Pie','Product'),
('Plate','Not a Product'),
('Bucket','Not a Product'),
('Chequebook','Not a Product'),
('French Toast','Product'),
('French Toast','Product'),
('Banana','Product'),
('Banana','Product'),
('Banana','Product');

✓

insert into wp_postmeta (post_id, meta_value) values
(1,10),
(2,5),
(3,9),
(4,8),
(5,11),
(6,12),
(7,10),
(8,6),
(9,1),
(10,1),
(11,7),
(12,2),
(13,2);

✓

-- Deleting all duplicate products in wp_posts table 
DELETE FROM wp_posts 
WHERE  id IN (SELECT id 
              FROM   (SELECT id, 
                             post_title, 
                             post_type, 
                             meta_value 
                      FROM   (SELECT wp_posts.id, 
                                     wp_postmeta.post_id, 
                                     post_title, 
                                     post_type, 
                                     meta_value, 
                                     Row_number() 
                                       OVER( 
                                         partition BY post_title 
                                         ORDER BY wp_postmeta.meta_value) rn 
                              FROM   wp_postmeta 
                                     JOIN wp_posts 
                                       ON wp_postmeta.post_id = wp_posts.id 
                              WHERE  wp_posts.post_type = 'Product' 
                                     AND wp_postmeta.meta_key = '_regular_price' 
                             ) t 
                      WHERE  t.rn <> 1) AS aliasx); 

✓

-- Deleting all corresponding wp_postmeta.post_ids that don't have a match in wp_posts.id after the duplicate deletion above
DELETE pm 
FROM   wp_postmeta pm 
WHERE  post_id IN (SELECT post_id 
                   FROM  (SELECT post_id 
                          FROM   wp_postmeta pm 
                                 LEFT JOIN wp_posts p 
                                        ON p.id = pm.post_id 
                          WHERE  p.id IS NULL 
                                 AND p.post_type = "product") i) 

✓

db小提琴here