Question

SELECT 
  p.ID, p.post_name as _slug, 
  p.post_title as _title, 
  p.post_modified as _updated, 
  m1.meta_value as _symbol,
  CONVERT(SUBSTRING_INDEX(m2.meta_value,'-',-1), INTEGER) as _rank 
FROM wp_posts AS p 
  LEFT JOIN wp_postmeta m1 ON p.id = m1.post_id AND m1.meta_key = '_cc_symbol' 
  LEFT JOIN wp_postmeta m2 ON p.id = m2.post_id AND m2.meta_key = '_cc_rank' 
where 
  p.post_type='cryptocurrency' ORDER by p.ID asc LIMIT 1 OFFSET 0

此查询在MySQL软件版本中不起作用：5.6.35-81.0

＃1064 - 您的SQL语法出错;检查与MySQL服务器版本对应的手册，以获得正确的语法在'INTEGER附近'为_rank，FROM wp_posts AS p LEFT JOIN wp_postmeta m1 在第1行打开p.id = m1.post'

提前致谢

Answer 1

在MySQL中，使用unsigned或signed代替int。我更喜欢cast()到convert()：

CAST(SUBSTRING_INDEX(m2.meta_value, '-', -1) as unsigned) as _rank

（在旧版本的MySQL中，convert()仅在字符集之间转换，而不是类型。）

或者更简单地说，使用静默转换：

(SUBSTRING_INDEX(m2.meta_value, '-', -1) + 0) as _rank

MySQL Query在5.6中不起作用

1 个答案: