具有不同列数的 UNION 多选语句

Question

我怎样才能联合这些选择语句，每个表都有不同的列数？

(SELECT title, description, full_description, keywords, option1, option2, option3, option4, option5, option6, option7, option8 FROM articles WHERE title LIKE ? OR description LIKE ? OR full_description LIKE ? OR keywords LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?) 
UNION ALL 
(SELECT title, description, full_description, keywords, option1, option2, option3, option4, option5, option6, option7, option8 FROM news WHERE title LIKE ? OR description LIKE ? OR full_description LIKE ? OR keywords LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?) 
UNION ALL 
(SELECT title, description, full_description, keywords, option1, option2, option3, option4, option5, option6, option7, option8 FROM products WHERE title LIKE ? OR description LIKE ? OR full_description LIKE ? OR keywords LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?) 
UNION ALL 
(SELECT title, description, option1, option2, option3, option4, option5, option6, option7, option8 FROM gallery_images WHERE title LIKE ? OR description LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?) 
UNION ALL 
(SELECT title, description, option1, option2, option3, option4, option5, option6, option7, option8 FROM pages WHERE title LIKE ? OR description LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?)

我收到此错误：

The used SELECT statements have a different number of columns

Answer 1

简单地说：您不能 - 您必须在那些列数少于最大列数的子查询中添加一些空白列（例如 NULL as blank1）

Answer 2

只需使用 NULL 值作为缺失字段的占位符。

这应该可行：

(SELECT title, description, full_description, keywords, option1, option2, option3, option4, option5, option6, option7, option8 FROM articles WHERE title LIKE ? OR description LIKE ? OR full_description LIKE ? OR keywords LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?) 
UNION ALL 
(SELECT title, description, full_description, keywords, option1, option2, option3, option4, option5, option6, option7, option8 FROM news WHERE title LIKE ? OR description LIKE ? OR full_description LIKE ? OR keywords LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?) 
UNION ALL 
(SELECT title, description, full_description, keywords, option1, option2, option3, option4, option5, option6, option7, option8 FROM products WHERE title LIKE ? OR description LIKE ? OR full_description LIKE ? OR keywords LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?) 
UNION ALL 
(SELECT title, description, NULL AS full_description, NULL AS keywords, option1, option2, option3, option4, option5, option6, option7, option8 FROM gallery_images WHERE title LIKE ? OR description LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?) 
UNION ALL 
(SELECT title, description, NULL AS full_description, NULL AS keywords, option1, option2, option3, option4, option5, option6, option7, option8 FROM pages WHERE title LIKE ? OR description LIKE ? OR option1 LIKE ? OR option2 LIKE ? OR option3 LIKE ? OR option4 LIKE ? OR option5 LIKE ? OR option6 LIKE ? OR option7 LIKE ? OR option8 LIKE ?)