Question

我有以下查询：

SELECT X.ID, X.NAME, CASE R.ID WHEN NOT NULL THEN 1 ELSE 0 END ISRELATED
FROM TABLE X
INNER JOIN RELATIVE R ON R.NAMEID = X.ID

我试图让结果看起来像这个结构，而不是从表X中拉出任何重复的行：

ID
NAME
ISRELATED (boolean)

有什么建议吗？感谢。

Answer 1

使用INNER JOIN将仅返回X中具有R中相应行的那些行。使用Left outer join代替。

SELECT DISTINCT X.ID, X.NAME, CASE WHEN R.ID IS NOT NULL THEN 1 ELSE 0 END ISRELATED 
FROM TABLE X 
LEFT OUTER JOIN RELATIVE R ON R.NAMEID = X.ID

Answer 2

试试这个

SELECT DISTINCT X.ID, X.NAME, CASE WHEN R.ID IS NOT NULL THEN 1 ELSE 0 END ISRELATED 
FROM TABLE X 
INNER JOIN RELATIVE R ON R.NAMEID = X.ID

Answer 3

我认为您在CASE中有错误，必须使用LEFT JOIN

SELECT DISTINCT
    X.ID, 
    X.NAME, 
    CASE WHEN R.ID IS NOT NULL THEN 1 ELSE 0 END ISRELATED 
FROM TABLE X 
LEFT JOIN RELATIVE R ON R.NAMEID = X.ID

如何使用Join作为Select列

3 个答案: