Question

SQL Server 2000

使用超过20个视图，所有视图都是与table1的内连接（id和value1和value2）

表1

ID Value1 Value2

001 100 null
001 200 null
001 300 null
001 400 null
001 200 null

或

ID Value1 Value2

001 null 100 
001 null 200 
001 null 300 
001 null 400 
001 null 200

表2

ID value1 value2

....
....

some data's

从table1

，value1或value2应始终为null。现在的问题是，如果 value1或value2列为null，则输出显示为null，因为所有视图都是内部连接，其id为，value1，value2

我想用条件进行内部连接，如果value1不为null，则使用内部连接 value1或者value2不为null，则内连接为value2

像这样查询

Select * from table2 inner join with table1 on tabel2.id = table1.id and if table1.value1 is null then table2.value2 = table1.value2 or
else table2.value1 = table1= value1 end if

如何查询上述条件

需要SQL查询帮助

Answer 1

以下是否会有以下工作？

SELECT * FROM table2
INNER JOIN WITH table1 ON table2.id = table1.id
    AND (table1.value1 = table2.value1 OR table1.value1 IS NULL)
    AND (table1.value2 = table2.value2 OR table1.value2 IS NULL)

我认为如果你有一个大数据集，这可能会很慢......

Answer 2

您是否尝试过coalesce(value1, value2)？

Answer 3

试试这个解决方案：

Select * 
from table2 
inner join table1 on (tabel2.id = table1.id 
                      and table1.value1 is null 
                      and table2.value2 = table1.value2) 
                  or ( table2.value1 = table1.value1 )

Answer 4

SELECT * FROM table2 t2
INNER JOIN WITH table1 t1 ON table2.id = table1.id
On (CASE WHEN t1.value1 is null then t1.value2=t2.value2 else t1.value1=t2.value1)
and
(CASE WHEN t2.value1 is null then t2.value2=t1.value2 else t2.value1=t1.value1)

如何使用条件进行内连接...？

4 个答案: