半保证没有白痴:

declare @max int;  
select @max = max(key) from table;  
dbcc checkident(table,reseed,@max)

http://sqlserverplanet.com/tsql/using-dbcc-checkident-to-reseed-a-table-after-delete

You do not want to do this in general. Reseed can create data integrity problems. It is really only for use on development systems where you are wiping out all test data and starting over. It should not be used on a production system in case all related records have not been deleted (not every table that should be in a foreign key relationship is!). You can create a mess doing this and especially if you mean to do it on a regular basis after every delete. It is a bad idea to worry about gaps in you identity field values.

DBCC CHECKIDENT('databasename.dbo.tablename', RESEED, number)

如果number = 0，那么在下一次插入时，自动递增字段将包含值1

如果number = 101，那么在下一次插入时，自动递增字段将包含值102

一些额外的信息…可能对你有用 在上述查询中给出自动递增数之前，必须确保现有表的自动递增列包含的值小于该数。

要从表(table1)中获取列(column_name)的最大值，可以使用以下查询

 SELECT MAX(column_name) FROM table1

我想添加这个答案是因为DBCC checkident -方法在对表使用模式时会产生问题。用这个来确定:

DECLARE @Table AS NVARCHAR(500) = 'myschema.mytable';
DBCC CHECKIDENT (@Table, RESEED, 0);

如果需要检查操作是否成功，请使用

SELECT IDENT_CURRENT(@Table);

在上面的例子中应该输出0。

如果你正在使用MySQL，试试这个:

ALTER TABLE tablename AUTO_INCREMENT = 1

半保证没有白痴:

declare @max int;  
select @max = max(key) from table;  
dbcc checkident(table,reseed,@max)

http://sqlserverplanet.com/tsql/using-dbcc-checkident-to-reseed-a-table-after-delete