擅长:python、mysql、java
<p>必须在not exist子句中使用subselect:</p>
<pre><code>getresult = """SELECT serialnumber, size FROM inventory i99
WHERE season = 74 AND location = 99
AND NOT EXISTS (SELECT serialnumber FROM inventory i1
WHERE i1.serialnumber = i99.serialnumber
AND i1.size = i99.size
AND i1.location = 1)"""
</code></pre>
<p>这是我知道的在SQL级别直接查找不存在的值的唯一方法,因为<code>IS NULL</code>即使在外部连接测试中,值也是原始表,而不是select返回的值。你知道吗</p>