Question

我有2个表，有4,00,000个记录：表A（列：数量和分类）和表B（列：数量和分类）。我必须从表中提取不相等的代码。

SELECT DISTINCT
  a.number,
  a.classification,
  b.classification
FROM TableA a
LEFT OUTER JOIN TableB b
  ON b.number = a.number
  AND a.classification != b.classification;

此查询会填充不相等的所有记录，包括BLANK行。我想要一个没有空行的查询。

所以我在查询中添加了另一行：

SELECT DISTINCT
  a.number,
  a.classification,
  b.classification
FROM TableA a
LEFT OUTER JOIN TableB b
  ON b.number = a.number
  AND a.classification != b.classification
  AND a.classification IS NOT NULL
  AND b.classification IS NOT NULL;

但是上面的查询运行了35分钟并且没有生成任何记录。有人可以帮我替代吗？

Answer 1

你快到了那里：

select distinct a.number, a.classification, b.classification 
from      TableA a 
left join TableB b 
       on b.number = a.number
      and a.classification = b.classification
where b.number is null;

首先，您要查找相同的那些，然后选择那些未找到的那些。

或者，因为你显然想要b.classification值：

select distinct a.number, a.classification, b.classification 
from      TableA a 
left join TableB b 
       on b.number = a.number
where a.classification != b.classification;

Answer 2

请试试这个 - ＆gt; a.classification＆lt;＆gt; ＆＃39;＆＃39;

select distinct a.number, a.classification, b.classification from TableA a left outer join TableB b on b.number = a.number and a.classification != b.classification AND a.classification <> '' AND a.classification IS NOT NULL AND b.classification <> '' AND b.classification IS NOT NULL

SQL查询＆lt;＆gt;甚至填充空白行

2 个答案: