如何在MySQL中使用“COUNT”条件？

Question

我收到错误在此查询，

SELECT count(if(state=0)) FROM `nagios`.`nagios_hostchecks` 
where `nagios_hostchecks`.`start_time` like '%2012-01-02%' 
and `nagios_hostchecks`.`host_object_id`=60; 

Answer 1

如何：

SELECT count(*) 
FROM `nagios`.`nagios_hostchecks` 
WHERE `nagios_hostchecks`.`start_time` like '%2012-01-02%' 
    AND 
`nagios_hostchecks`.`host_object_id`=60 
    AND 
`state` = 0; 

Answer 2

只是快速猜测，不检查Nagios的架构

SELECT count(*) FROM nagios.nagios_hostchecks 
WHERE state=0 AND nagios_hostchecks.start_time like '%2012-01-02%' 
AND nagios_hostchecks.host_object_id=60;