Question

我试图通过仅返回年份将Max（年）从日期字段变为Varchar字段我希望有人可以提供帮助。

这就是我到目前为止所做的。

  UPDATE MasterDraft
            SET 
            Last_title_changed = (select Max((deed_dt) ) 
            From APPRAISAL_Deed_History )
            WHERE MasterDraft.Prop_ID = APPRAISAL_Deed_History.prop_id

这是我的源表：

+---------+------------+
| prop_id |  deed_dt   |
+---------+------------+
|      40 | 1988-07-22 |
|      40 | 1984-03-01 |
|      40 | 2005-07-12 |
|      40 | 1983-07-01 |
|      40 | 1992-01-31 |
|      40 | 1983-01-01 |
|      40 | 1990-01-31 |
+---------+------------+

MasterDraft.Last_title_Changed上的输出应为2005

Answer 1

那应该是Max(YEAR(deed_dt))

编辑：那么你想更新所有记录并使用prop id的最大年份？然后将where子句移动到子选择。在内部查询之外不知道APPRAISAL_Deed_History.prop_id。

  UPDATE MasterDraft
    SET Last_title_changed = 
    (
      select Max( Year(deed_dt) ) 
      from APPRAISAL_Deed_History 
      where APPRAISAL_Deed_History.prop_id = MasterDraft.Prop_ID
    );

Answer 2

    UPDATE MasterDraft
    SET Last_title_changed = Max(YEAR(deed_dt)
    From APPRAISAL_Deed_History INNER JOIN MasterDraft
    WHERE MasterDraft.Prop_ID = APPRAISAL_Deed_History.prop_id

使用MAX DATE更新SQL表

2 个答案: