Question

我希望比较两组数据并显示两组的完整联合，并添加列以显示行是否出现在第1组，第2组或两者中。我在T-SQL

工作

Table A  
|[ID] | [Movie] | [Year] |  
|-----|---------|--------|  
| 1   | Movie1  | Year1  |  
| 2   | Movie2  | Year2  |  
| 3   | Movie3  | Year3  |   

Table B  
|[ID] | [Movie] | [Year] |   
|-----|---------|--------|  
| 2   | Movie2  | Year2  |  
| 3   | Movie3  | Year3  |  
| 4   | Movie4  | Year4  |   


Desired Result:  
|[ID] | [Movie] | [Year] | [In Set A?] | [In Set B?] |  
|-----|---------|--------|-------------|-------------|  
| 1   | Movie1  | Year1  |    Yes      |     No      |  
| 2   | Movie2  | Year2  |    Yes      |     Yes     |  
| 3   | Movie3  | Year3  |    Yes      |     Yes     |  
| 4   | Movie4  | Year4  |    No       |     Yes     |

这可以在SQL中完成吗？我决定让添加的列只有1列，其中输出为A，B或两者。

Answer 1

你可以使用FULL JOIN和COALESCE，假设你可以加入ID：

SELECT COALESCE(a.ID,b.ID)as ID
     , COALESCE(a.Movie,b.Movie) as Movie
     , COALESCE(a.Year,b.Year) as Year
     , CASE WHEN a.ID IS NULL THEN 'NO' ELSE 'YES' END as InSetA
     , CASE WHEN b.ID IS NULL THEN 'NO' ELSE 'YES' END as InSetB
FROM TableA a
FULL JOIN TableB b
 ON a.ID = b.ID

演示：SQL Fiddle

您还可以将最后一部分合并到一个字段中：

SELECT COALESCE(a.ID,b.ID)as ID
     , COALESCE(a.Movie,b.Movie) as Movie
     , COALESCE(a.Year,b.Year) as Year
     , CASE WHEN a.ID IS NULL THEN 'In B Only'
            WHEN b.ID IS NULL THEN 'In A Only'
            ELSE 'In Both'
       END as InTable    
FROM TableA a
FULL JOIN TableB b
 ON a.ID = b.ID

Answer 2

您可以使用union all：

执行此操作

select id, movie, year,
       (case when max(inA) = 1 then 'Yes' else 'No' end) as inA,
       (case when max(inB) = 1 then 'Yes' else 'No' end) as inB
from ( select id, movie, year, 1 as InA, 0 as InB
       from tableA
       union all
       select id, movie, year, 0, 1
       from tableB
     ) t
group by id, movie, year

这与full outer join解决方案略有不同。如果两个表中都有重复项，那么该解决方案可以将行相乘。此解决方案将删除重复项，即使在表中也是如此，因此多行将缩小到一行。

比较SQL表：显示完整集和任何差异

2 个答案: