如何在SQLSERVER中快速有条件删除海量数据
1.SQLSERVER数据库改bit类型为 not Boolean(即,true改成false;false改成true)例:update 表 set bit字段=bit字段-1
最近有个朋友问我，他说他在SQLSERVER删除几百万到几千万数据是显的很慢，帮他分析了一下，提了一些以下意见，或许对很多人有用，再者也好长没写过BLOG了，一起探讨一下
如果你的硬盘空间小，并且不想设置数据库的日志为最小(因为希望其他正常的日志希望仍然记录)，而且对速度要求比较高，并清除所有的数据建议你用turncate table1,因为truncate 是DDL操作，不产生rollback，不写日志速度快一些，然后如果有自增的话，恢复到1开始，而delete会产生rollback，如果删除大数据量的表速度会很慢，同时会占用很多的rollback segments，同时还要记录下G级别的日志 ；当然如果有条件删除比如where time
选出您所需要保留的记录到新的表。如果您使用 Full Recovery Mode
根据Select INTO的记录数,日志可能会比较大
Select * into Table2 From Table1 Where Time > = '2006-03-10'
然后直接Truncate Table1。无论何种恢复模式都不会进行日志记录
Truncate table Table1
最后对Table2进行改名为Table1
EC sp_rename 'Table2', 'Table1'
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