mysql - 在 UNION 中显示 JOIN 表中的所有字段？

Question

如何tariff_data使用 JOIN 显示已包含在 UNION 中的表中的某些字段？

例如：

SELECT  X.* FROM
    (
         SELECT phone_id, tariff_id, active  FROM table1 WHERE id = 5
      UNION
          SELECT dgt.phone_id, tns.tariff_id, dgt.active  FROM  table2 AS dgt 
                JOIN tariff_data AS tns ON tns.something = dgt.something
          WHERE id = 5
    ) as X

Answer 1

SELECT  X.* FROM
(
    SELECT phone_id, tariff_id, active, null as "somefield"  FROM table1 WHERE id = 5
      UNION
    SELECT dgt.phone_id, tns.tariff_id, dgt.active, tns.somefield FROM  table2 AS dgt 
            JOIN tariff_data AS tns ON tns.something = dgt.something
    WHERE id = 5
) as X

Answer 2

您需要在两个 Select 语句中包含来自关税数据的字段，将第一个设置为 null 或您喜欢的任何内容：

SELECT  X.* FROM
(
    SELECT phone_id, tariff_id, active, null as "somefield"  FROM table1 WHERE id = 5
      UNION
    SELECT dgt.phone_id, tns.tariff_id, dgt.active, tns.somefield FROM  table2 AS dgt 
            JOIN tariff_data AS tns ON tns.something = dgt.something
    WHERE id = 5
) as X