mysql如果列为空，则选择，如果不为空，则应用条件

如果列为空或不为空，我在应用某些条件时遇到了一些困难

我的表格如下：

CREATE TABLE `meets` (
    `id` INT,
    `scheduled` VARCHAR(255),
    `status` INT
);

INSERT INTO meets(id,scheduled,status) VALUES (1,'','1');
INSERT INTO meets(id,scheduled,status) VALUES (2,'','2');
INSERT INTO meets(id,scheduled,status) VALUES (2,'1613220631','3'); // in 30 minutes
INSERT INTO meets(id,scheduled,status) VALUES (2,'1644756631','3'); // 2022

到目前为止，我所做的是：

SELECT * FROM meets WHERE FROM_UNIXTIME(scheduled) BETWEEN DATE_SUB(NOW(), INTERVAL 30 MINUTE) AND DATE_SUB(NOW(), INTERVAL -30 MINUTE) ORDER BY `id` DESC

以上仅选择在随后/过去30分钟内具有时间戳的记录

除了该记录之外，我还需要选择记录id 1，因为它的状态==1

所以基本上

if scheduled column is empty, check for status to be 1 and select if true;
if scheduled column is timestamp, apply condition from the query posted above; 

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有什么想法吗？谢谢大家!

可以使用union添加缺少的行

    SELECT * 
    FROM meets 
    WHERE FROM_UNIXTIME(scheduled) 
    BETWEEN DATE_SUB(NOW(), INTERVAL 30 MINUTE) AND DATE_SUB(NOW(), INTERVAL -30 MINUTE) 
    ORDER BY `id` DESC
    UNION 
    select * from meets where scheduled = '' AND status = 1

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又快又简单，谢谢！