--> 测试数据：#
if object_id('tempdb.dbo.#') is not null drop table #
create table #(Id int, state varchar(8), flag int, createtime datetime, updatetime1 datetime, deletetime datetime, updatetime3 datetime)
insert into #
select 1, '创建', null, '2011-07-07', null, null, null union all
select 2, '删除', null, null, null, '2011-08-07', null union all
select 3, '更新', 1, null, '2011-08-13', null, null union all
select 4, '更新', 3, null, null, null, '2011-08-08'


select Id, state, dealtme=coalesce(createtime, updatetime1, deletetime, updatetime3)  from #
/*
Id          state    dealtme
----------- -------- -----------------------
1           创建       2011-07-07 00:00:00.000
2           删除       2011-08-07 00:00:00.000
3           更新       2011-08-13 00:00:00.000
4           更新       2011-08-08 00:00:00.000
*/