如何逐块更新巨大的记录
- 作者: 充电5分钟_装B3小时
- 来源: 51数据库
- 2023-02-07
问题描述
我有大约 500 000 的数据.我需要将 First name 和 Second name 的数据更新为大写
I have data around 500 000. I need to update the data of First name and Second name to capital letters
我的样本数据:
declare @T table(Firstname varchar(max),Secondname varchar(max)) insert into @T values ('ch bhaskar rao ','sridhar kolla ') insert into @T values ('hemanth kumar','varun chenna-reddy') insert into @T values ('mohan vara prasad','raju t d p durga raju') insert into @T values ('police mutual','police mutual')
我的脚本:
;WITH CTE AS ( select ( select upper(T.N.value('.', 'char(1)')), lower(stuff(T.N.value('.', 'varchar(max)'), 1, 1, ''))+(CASE WHEN RIGHT(T.N.value('.', 'varchar(max)'), 1)='-' THEN '' ELSE ' ' END) from X.Secondname.nodes('/N') as T(N) for xml path(''), type ).value('.', 'varchar(max)') As Secondname from ( select cast('<N>'+replace(replace(replace(Secondname, ' ', '</N><N>'),' ', '</N><N>'),'-','-</N><N>') +'</N>' as xml) as Secondname from @T ) as X ) UPDATE T SET Secondname = C.Secondname FROM CTE C INNER JOIN @T T ON T.Secondname = C.Secondname Select Secondname from @T
当数据大约为 10 000 条记录时它工作正常,但是当我尝试更新大约 500 万条记录时系统挂断了.如何像 10000 和 10000 那样逐块更新,以免系统负担?
It is working fine when data is around 10 000 records but system getting hanged up when I'm trying to update huge records around 5 millions. How to update chunk by chunk like 10000 and again 10000, so that system will not burdened?
推荐答案
您可以像下面提到的那样分块更新表格:
You can update the table in chunks like mentioned below:
declare @i int = 2 declare @j int = 1 while @j > 0 begin begin transaction update top (@i) a set a.firstname = upper(a.firstname), a.secondname = upper(a.secondname) from aa as a where a.firstname collate latin1_general_cs_as <> upper(a.firstname) set @j = @@rowcount commit transaction end
您可以根据需要更改上述代码.如果这有帮助,请告诉我.
you can change the above code as per your needs. Let me know if this helps.
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