如何在mysql查询中获取Select Field Value Lenght

Question

这是我的示例代码，如果有人可以解释，请告诉我MySQL的语法......

SELECT s.sales_id,s.pid,s.quantity,IFNULL((SELECT i.invoice_id FROM
invoice AS i WHERE i.checkin_id NOT IN (SELECT crt.checkin_id FROM 
checkin_request_ticket as crt WHERE crt.salvage_part='1') AND 
i.invoice_id=s.sales_id),s.quantity) as checkquan
FROM sales as s 

Answer 1

length(s.sales_id)给出长度