Question

我正在尝试阅读教程并在sql子查询上找到有关特定目的的语法问题，但我似乎找不到合适的词语来描述我的问题。

表格 - 部分描述

+------------+------------+------------+
| ID         | Part #     |    Type    |
+------------+------------+------------+
| 1          |     123    |      1     |
| 2          |     456    |      2     |
| 3          |     123    |      3     |
| 4          |     789    |      4     |
| 5          |     123    |      4     |
| 6          |     789    |      2     |
| 7          |     123    |      2     |
+------------+------------+------------+

我基本上需要找到类型值为“2”和“4”的任何部件号，而不是其中之一。

我觉得它应该非常简单，但我似乎无法得到正确的结果

Answer 1

您可以使用WHERE，GROUP BY和HAVING子句的组合来获取结果。 HAVING子句中的关键是计算WHERE过滤器中包含的不同项：

select [part #]
from partDescriptions
where type in (2, 4)
group by [part #]
having count(distinct type) = 2;

请参阅SQL Fiddle with Demo

如果你只想返回只有2和4类型的部分，那么你可以扩展一下：

select PartNum
from yourtable
where type in (2, 4)
  and partnum not in (select partnum
                      from yourtable 
                      where type not in (2, 4))
group by PartNum
having count(distinct type) = 2

请参阅Demo

Answer 2

SELECT *
FROM PartDesciption P
WHERE EXISTS (SELECT * FROM PartDesciption WHERE ID = P.ID AND Type = 2) AND
      EXISTS (SELECT * FROM PartDesciption WHERE ID = P.ID AND Type = 4)

Answer 3

这样可行：

SELECT PartNumber, COUNT(*)
FROM Table
WHERE Type IN (2, 4)
GROUP BY PartNumber HAVING COUNT(*) > 1

Answer 4

您希望零件号缺少两个必需值。以下查询似乎很复杂，但它比这类问题的一些更简单的解决方案更容易推广到类似的要求。

如果您有一个列出所有有效部件号的表，您可以在最外面的SELECT中使用它以避免需要SELECT DISTINCT。

WITH RequiredParts(p) AS (
  SELECT 2 UNION ALL SELECT 4
)
  SELECT DISTINCT([Part #]) AS [Part #]
  FROM [Part Descriptions] AS PD
  WHERE NOT EXISTS (
    SELECT * FROM RequiredParts AS RP
    WHERE NOT EXISTS (
      SELECT * FROM [Part Descriptions] AS PD2
      WHERE PD2.[Part #] = PD.[Part #]
      AND PD2.[Type] = RP.p
    )
  )

Sql - 如何搜索具有两个特定变量的不同行

4 个答案: