添加union all子句：

SELECT * FROM table1 WHERE serialnumber NOT IN 
(
    SELECT serialnumber FROM table2
    UNION ALL
    SELECT serialnumber FROM table3
    UNION ALL
    SELECT serialnumber FROM table4
...
)

代替子查询，您可以执行更高效的 Left Join . 我们可以简单地从 table1 其他的table( table1 留给他们所有人的table）。现在， serialnumber 其他表中不存在的值将具有 null 值post join。所以，我们可以简单地使用 Where serialnumber IS NULL 要筛选的条件：

SELECT t1.* FROM table1 AS t1
LEFT JOIN table2 AS t2 ON t2.serialnumber = t1.serialnumber 
LEFT JOIN table2 AS t3 ON t3.serialnumber = t1.serialnumber 
LEFT JOIN table2 AS t4 ON t4.serialnumber = t1.serialnumber 
LEFT JOIN table2 AS t5 ON t5.serialnumber = t1.serialnumber 
WHERE t2.serialnumber IS NULL AND 
      t3.serialnumber IS NULL AND 
      t4.serialnumber IS NULL AND 
      t5.serialnumber IS NULL