MySQL 查询在 5.6 中不起作用

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

This query is not working in MySQL Software version: 5.6.35-81.0

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'INTEGER) as _rank, FROM wp_posts AS p LEFT JOIN wp_postmeta m1 ON p.id = m1.post' at line 1

Thanks in advance

Answer 1

In MySQL, use unsigned or signed instead of int . I prefer cast() to convert() :

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

(In older versions of MySQL, convert() only converted between character sets, not types.)

Or, more simply, use silent conversion:

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