使用的是MSSQLSever.
使用
select top 50 percent * from [table] order by newid()
可以随机选取table的50%行。
使用
update randowmRecords set randowmRecords.[column] = [value] from (select top 50 percent * from [table] order by newid()) as randowmRecords
可以随机更新50%行的对应列
Ref: