Sql 使用上一行更新行

我有下表：

我正在尝试编写一个更新，用先前大于零的值填充零

我尝试过以下问题，但没有成功

一,

如果有人能帮助我，我将非常感激

---

感谢

SQL Server中的一种方法使用可更新的CTE和窗口函数：

with toupdate as (
      select tl.*,
             max(Q_G_R_BUOM) over (partition by grp) as imputed_Q_G_R_BUOM
      from (select tl.*,
                   sum(case when Q_G_R_BUOM <> 0 then 1 else 0 end) over (order by id) as grp
            from testing_lag tl
           ) tl
     ) 
update toupdate
    set Q_G_R_BUOM = imputed_Q_G_R_BUOM
    where Q_G_R_BUOM = 0;

这个怎么样

--DROP TABLE #C
CREATE TABLE #C (ID INT, Q_G_R_BUOM INT)
INSERT INTO #C values(1, 1805)
INSERT INTO #C values(2, 0)
INSERT INTO #C values(3, 0)
INSERT INTO #C values(4, 4732)
INSERT INTO #C values(5, 0)
INSERT INTO #C values(6, 0)

select * from #c

如果您的表中有空值，则解决方案会有所不同

SELECT ID,CASE WHEN Q_G_R_BUOM >0
            THEN Q_G_R_BUOM
            ELSE (SELECT max(Q_G_R_BUOM)
                  FROM #C
                  WHERE ID <= t.ID)
       END AS X
FROM #C t 

---

感谢您的回答，请评论更新必须基于Asc ID，此查询是否以这种方式工作？@LaurenorubioaGuillar。这两个答案都依赖于

id

来定义表的顺序。两者都采用基于id的“previous”非

0

值。非常感谢您的支持

update tl
    set q_g_r_buom = tl2.q_g_r_buom
    from test_lag tl cross apply
         (select top (1) tl2.*
          from test_lag tl2
          where tl2.q_g_r_buom <> 0 and
                tl2.id < tl.id
          order by tl2.id
         ) tl2
    where tl.q_g_r_buom = 0

--DROP TABLE #C
CREATE TABLE #C (ID INT, Q_G_R_BUOM INT)
INSERT INTO #C values(1, 1805)
INSERT INTO #C values(2, 0)
INSERT INTO #C values(3, 0)
INSERT INTO #C values(4, 4732)
INSERT INTO #C values(5, 0)
INSERT INTO #C values(6, 0)

select * from #c

SELECT ID,CASE WHEN Q_G_R_BUOM >0
            THEN Q_G_R_BUOM
            ELSE (SELECT max(Q_G_R_BUOM)
                  FROM #C
                  WHERE ID <= t.ID)
       END AS X
FROM #C t 

DROP TABLE #C
CREATE TABLE #C (ID INT, Q_G_R_BUOM INT)
INSERT INTO #C values(1, 1805)
INSERT INTO #C values(2, null)
INSERT INTO #C values(3, null)
INSERT INTO #C values(4, 4732)
INSERT INTO #C values(5, null)
INSERT INTO #C values(6, null)

select * from #c

SELECT ID,
COALESCE(Q_G_R_BUOM,
MAX(COALESCE(Q_G_R_BUOM,'')) OVER (ORDER BY ID  ROWS BETWEEN UNBOUNDED PRECEDING AND  1 PRECEDING)) AS Name
FROM #c