UPDATE SC SET SC.S#='S005' WHERE S#='S001' ---------- 把表字段为S#的'S001'全部修改成'S005' 这样算批量处理吗
是后面跟select查出来的比如:update news_newstab set n_modifyDate = (select n_createdate from news_newstab t0 where n_id = t0.n_id) where n_modifyDate is null
update news_newstab set n_modifyDate = n_createdate where n_modifyDate is null
create table test(time datetime) insert test select '2009-1-2' union all select '2003-11-2' union all select '2004-3-21' union all select '2005-3-22' union all select '2006-5-2' go select * from test time ------------------------------------------------------ 2009-01-02 00:00:00.000 2003-11-02 00:00:00.000 2004-03-21 00:00:00.000 2005-03-22 00:00:00.000 2006-05-02 00:00:00.000 update test set time=(select getdate()) where time='2006-5-2'; select * from test(所影响的行数为 1 行)time ------------------------------------------------------ 2009-01-02 00:00:00.000 2003-11-02 00:00:00.000 2004-03-21 00:00:00.000 2005-03-22 00:00:00.000 2009-02-05 14:08:08.840(所影响的行数为 5 行) (所影响的行数为 5 行)
set col='some value'
where....
UPDATE SC
SET SC.S#='S005'
WHERE S#='S001'
----------
把表字段为S#的'S001'全部修改成'S005' 这样算批量处理吗
set n_modifyDate = (select n_createdate from news_newstab t0 where n_id = t0.n_id)
where n_modifyDate is null
set n_modifyDate = n_createdate
where n_modifyDate is null
create table test(time datetime)
insert test select '2009-1-2'
union all select '2003-11-2'
union all select '2004-3-21'
union all select '2005-3-22'
union all select '2006-5-2'
go
select * from test
time
------------------------------------------------------
2009-01-02 00:00:00.000
2003-11-02 00:00:00.000
2004-03-21 00:00:00.000
2005-03-22 00:00:00.000
2006-05-02 00:00:00.000
update test set time=(select getdate()) where time='2006-5-2';
select * from test(所影响的行数为 1 行)time
------------------------------------------------------
2009-01-02 00:00:00.000
2003-11-02 00:00:00.000
2004-03-21 00:00:00.000
2005-03-22 00:00:00.000
2009-02-05 14:08:08.840(所影响的行数为 5 行)
(所影响的行数为 5 行)
究竟是批量更新 某些字段得值成相同得值
还是 批量更新 某些字段得值成不同得值第一种 就用UPDATE来完成第二种得话似乎不能用一条语句实现
set n_modifyDate = t0.n_createdate from news_newstab,t0 where news_newstab.n_id = t0.n_id and news_newstab.n_modifyDate is null