如何仅从结果集中选择公共属性?

SELECT
    CASE WHEN COUNT(DISTINCT city) = 1 THEN MAX(city) ELSE NULL END AS city,
    CASE WHEN COUNT(DISTINCT state) = 1 THEN MAX(state) ELSE NULL END AS state,
    CASE WHEN COUNT(DISTINCT zip) = 1 THEN MAX(zip) ELSE NULL END AS zip
FROM Users
WHERE ID IN(1,2,3,4,5,6)

在其他答复之后:

SELECT
    CASE WHEN COUNT(DISTINCT NULLIF(city,'**NULL**')) = 1 THEN MAX(city) ELSE NULL END AS city,
    CASE WHEN COUNT(DISTINCT NULLIF(state,'**NULL**')) = 1 THEN MAX(state) ELSE NULL END AS state,
    CASE WHEN COUNT(DISTINCT NULLIF(zip,'**NULL**')) = 1 THEN MAX(zip) ELSE NULL END AS zip
FROM Users
WHERE ID IN(1,2,3,4,5,6)

如果列不可为null,或者如果要忽略null,则gbn的答案是正确的。但是,如果需要将空值视为不同的值,请尝试以下操作:

CASE WHEN COUNT(DISTINCT city) = 1 
      AND COUNT(city) = COUNT(*) 
     THEN MAX(city) ELSE NULL END AS city