Question

我如何编写导致以下内容的查询...

假设我的数据集看起来像这样：

| PersonId | LastName | FirstName | ProductType | ProductValue |
|----------|----------|-----------|-------------|--------------|
| P0000001 |  Bloggs  |    Joe    |      1      |      £15     |
| P0000001 |  Bloggs  |    Joe    |      1      |      £20     |
| P0000001 |  Bloggs  |    Joe    |      2      |      £10     |
| P0000001 |  Bloggs  |    Joe    |      3      |      £5      |
| P0000002 |    Doe   |   Jane    |      2      |      £25     |
| P0000002 |    Doe   |   Jane    |      3      |      £60     |
| P0000003 |   Brown  |    Jim    |      1      |      £20     |
| P0000003 |   Brown  |    Jim    |      3      |      £5      |

如果PersonId在ProductType = 1个记录集中至少有1次出现PersonId，则返回该PersonId的所有记录（即使从集合返回的其他记录的ProductType不是1）。

所以上面的数据集会像这样过滤：

| PersonId | LastName | FirstName | ProductType | ProductValue |
|----------|----------|-----------|-------------|--------------|
| P0000001 |  Bloggs  |    Joe    |      1      |      £15     |
| P0000001 |  Bloggs  |    Joe    |      1      |      £20     |
| P0000001 |  Bloggs  |    Joe    |      2      |      £10     |
| P0000001 |  Bloggs  |    Joe    |      3      |      £5      |
| P0000003 |   Brown  |    Jim    |      1      |      £20     |
| P0000003 |   Brown  |    Jim    |      3      |      £5      |

Jane Doe没有ProductType = 1的任何记录，所以她的所有记录都被过滤掉了。 Joe Bloggs和Jim Brown在ProductType = 1中至少有1条记录，因此在查询中返回了所有的记录。

Answer 1

您可以使用GROUP BY和HAVING子句：

SELECT PersonID, LastName, Firstname
FROM tbl
WHERE ProductType=1
GROUP BY PersonID, LastName, FirstName
HAVING COUNT(*) >=1

然后你使用IN子句：

SELECT * FROM tbl
WHERE PersonID IN (
  SELECT PersonID
  FROM tbl
  WHERE ProductType=1
  GROUP BY PersonID
  HAVING COUNT(*) >=1
)

Answer 2

您可以使用EXISTS执行此操作。像这样：

SELECT 
    * 
FROM 
    yourTable as tbl
WHERE EXISTS
    (
        SELECT
            NULL
        FROM
            yourTable AS tbl1
        WHERE
            yourTable.PersonId=tbl.PersonId
            AND tbl1.ProductType=1
    )

这将为您提供输出：

P0000001    Bloggs  Joe 1   £15
P0000001    Bloggs  Joe 1   £20
P0000001    Bloggs  Joe 2   £10
P0000001    Bloggs  Joe 3   £5
P0000003    Brown   Jim 1   £20
P0000003    Brown   Jim 3   £5

MS-Access - 查询以根据条件返回每个记录子集

2 个答案: