MySQL获取日期大于8个月的记录

Question

How do I get the records from a MySQL database where 'Last_updated' is greater than "8 months" or ("date is null") and ('Number_of_employees' is less and equal to 500)?

Table details:

CREATE TABLE `companies` (
  `company_id` int(11) NOT NULL AUTO_INCREMENT,
  `company_name` varchar(255) NOT NULL COMMENT, 
  `Number_of_employees` int(11) NOT NULL,
  `Last_updated` datetime NOT NULL,
  PRIMARY KEY (`company_id`),
  UNIQUE KEY `Company_Name` (`company_name`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

This is what I have so far:

SELECT * FROM companies WHERE Last_updated < (now() - interval 8 month);

Answer 1

Try this:

SELECT * 
FROM companies 
WHERE Number_of_employeesless <= 500 AND 
     (Last_updated IS NULL OR DATE(Last_updated) >= (CURRENT_DATE() - INTERVAL 8 MONTH));

OR

SELECT * 
FROM companies 
WHERE Number_of_employeesless <= 500 AND 
     (Last_updated IS NULL OR DATE(Last_updated) >= DATE_SUB(CURRENT_DATE(), INTERVAL 8 MONTH));

Answer 2

This should do the trick:

SELECT * FROM companies 
WHERE last_updated > (now() - INTERVAL 8 MONTHS) 
AND number_of_employeesless <= 500