如何执行条件SQL insert语句?

使用 WHERE NOT EXISTS 并检查是否与 > 时间-5分钟。

INSERT INTO MyTable (column1, column2) 
SELECT value1, value2 FROM DUAL
WHERE NOT EXISTS (SELECT * 
                  FROM MyTable 
                  WHERE EntryDate > DATE_SUB(NOW(), INTERVAL 5 MINUTE))

运行SELECT查询,查看程序中的结果,然后决定是否运行INSERT查询。

//Ask for how many rows are less than 5 minutes old
$count = mysql_result(mysql_query("SELECT COUNT(*) FROM MyTable WHERE MAX(EntryDate) > CURRENT_TIMESTAMP - INTERVAL 5 MINUTE"),0);
if ($count == 0) {
    mysql_query("INSERT INTO...");
    //I know I just INSERTed a row because I'm inside the conditional!
}

我不确定MySQL的语法,但您可能需要在这一部分用括号括起来:
(SELECT max(EntryDate) from MyTable) < DATE_SUB(CURRENT_DATE() INTERVAL 5 MINUTE