Sql server 左键连接一行并用单行填充空值'；s值

我有：

第一次订购服装类别中的物品：

    SELECT DISTINCT TOP 1
        od.SalesOrderNumber,
        a.OrderDate,
        od.hasClothing
    FROM History a
    INNER JOIN OrderDetails od
        ON a.SalesOrderNumber=od.SalesOrderNumber
    WHERE od.hasClothing = 1
    ORDER BY a.OrderDate ASC 

+------------------+------------+-------------+
| SalesOrderNumber | KeyDate    | hasClothing |
+------------------+------------+-------------+
| SO57673          | 2007-11-09 |           1 |
+------------------+------------+-------------+

而且

另一个查询生成：

+------------------+----------------+------------+
| SalesOrderNumber | CustomerAltKey | OrderDate  |
+------------------+----------------+------------+
| SO44063          | AW00011240     | 2005-08-30 |
| SO51205          | AW00011240     | 2007-07-03 |
| SO57673          | AW00011240     | 2007-11-09 |
| SO57953          | AW00011240     | 2007-11-14 |
+------------------+----------------+------------+

我试图将两个表连接起来并生成：

+------------------+----------------+------------+----------------------+
| SalesOrderNumber | CustomerAltKey | OrderDate  | OrderDate >= KeyDate |
+------------------+----------------+------------+----------------------+
| SO44063          | AW00011240     | 2005-08-30 |                    0 |
| SO51205          | AW00011240     | 2007-07-03 |                    0 |
| SO57673          | AW00011240     | 2007-11-09 |                    1 |
| SO57953          | AW00011240     | 2007-11-14 |                    1 |
+------------------+----------------+------------+----------------------+

我在SalesOrderNumber、OrderDate等上尝试了

左外部联接

，并尝试将空值合并到

2007-11-09

日期中。。。但我尝试过的一切都失败了。我刚刚得到：

+------------------+----------------+------------+----------------------+
| SalesOrderNumber | CustomerAltKey | OrderDate  | OrderDate >= KeyDate |
+------------------+----------------+------------+----------------------+
| SO44063          | AW00011240     | 2005-08-30 | NULL                 |
| SO51205          | AW00011240     | 2007-07-03 | NULL                 |
| SO57673          | AW00011240     | 2007-11-09 | 1                    |
| SO57953          | AW00011240     | 2007-11-14 | NULL                 |
+------------------+----------------+------------+----------------------+

---

有什么建议吗？这让我抓狂。

因为需要在查询结果中获取字段，所以需要使用用例语句

如果您发布表的定义，我们可以帮助您。同时，解决方案应该是这样的：

SELECT DISTINCT TOP 1
    od.SalesOrderNumber,
    a.OrderDate,
    od.hasClothing,
    CASE WHEN a.OrderDate >= od.KeyDate THEN 1 ELSE 0 END AS RESULT_FIELD_NAME
FROM History a
INNER JOIN OrderDetails od
    ON a.SalesOrderNumber=od.SalesOrderNumber
WHERE od.hasClothing = 1
ORDER BY a.OrderDate ASC 

---

希望能有所帮助。

基于您的示例数据，我创建了这个。但是，从示例数据来看，您似乎并不关心加入

salesfordernumber

。因此，我

交叉连接

对集合进行加密，以处理预期的输出

SELECT 
    r.SalesOrderNumber,r.CustomerAltKey,r.OrderDate,
    [OrderDate>=KeyDate]=CAST(CASE WHEN l.KeyDate<=r.OrderDate THEN 1 ELSE 0 END AS BIT)
FROM
    (
        SELECT SalesOrderNumber='SO57673',KeyDate='20071109',hasClothing=1
    ) AS l
    CROSS JOIN (
        SELECT SalesOrderNumber='SO44063',CustomerAltKey='AW00011240',OrderDate='20050830' UNION ALL
        SELECT SalesOrderNumber='SO51205',CustomerAltKey='AW00011240',OrderDate='20070703' UNION ALL
        SELECT SalesOrderNumber='SO57673',CustomerAltKey='AW00011240',OrderDate='20071109' UNION ALL
        SELECT SalesOrderNumber='SO57953',CustomerAltKey='AW00011240',OrderDate='20071114' 
    ) AS r

---

添加问题相关表格的结构。这将帮助我们帮助您。至少添加正在使用的所有表的候选键和列。这是理解数据所必需的关于表的基本信息。因此，您基本上忽略了连接中的SalesOrderNumber，这就是所需的输出？

+------------------+----------------+-----------+--------------------+
| SalesOrderNumber | CustomerAltKey | OrderDate | OrderDate>=KeyDate |
+------------------+----------------+-----------+--------------------+
| SO44063          | AW00011240     |  20050830 |                  0 |
| SO51205          | AW00011240     |  20070703 |                  0 |
| SO57673          | AW00011240     |  20071109 |                  1 |
| SO57953          | AW00011240     |  20071114 |                  1 |
+------------------+----------------+-----------+--------------------+