那么如果使用浮點數據保存了精度大于其范圍的數據其會使用四舍五入的方法截斷。 MYSQL如下： mysql> create table dname(id1 float,id2 double,name varchar(20)); Query OK, 0 rows affected (0.08 sec) mysql> insert into dname values(1234567.123,1234567.123,'gaopeng'); Query OK, 1 row affected (0.00 sec) mysql> commit; Query OK, 0 rows affected (0.00 sec) mysql> select * from dname; +---------+-------------+---------+ | id1 | id2 | name | +---------+-------------+---------+ | 1234570 | 1234567.123 | gaopeng | +---------+-------------+---------+ 1 row in set (0.00 sec) 雖然進行了四舍五入，但是不會有任何報錯和警告，這是其標準決定的而不是數據庫本生。 可以看到1234567.123在FLOAT下被四舍五入為1234570，而DOUBLE類型沒有問題，那么我們 直接從數據文件中提取數據。 我還是使用了自己寫的小工具BCVIEW [root@hadoop1 test]# bcview dname.ibd 16 127 40 ****************************************************************** This Tool Is Uesed For Find The Data In Binary format(Hexadecimal) Usage:./bcview file blocksize offset cnt-bytes! file: Is Your File Will To Find Data! blocksize: Is N kb Block.Eg: 8 Is 8 Kb Blocksize(Oracle)! Eg: 16 Is 16 Kb Blocksize(Innodb)! offset:Is Every Block Offset Your Want Start! cnt-bytes:Is After Offset,How Bytes Your Want Gets! Edtor QQ:22389860! Used gcc version 4.1.2 20080704 (Red Hat 4.1.2-46) ****************************************************************** ----Current file size is :0.093750 Mb ----Current use set blockszie is 16 Kb current block:00000000--Offset:00127--cnt bytes:40--data is:00ffffffff0000000000010000000200260000000200260000000000000000ffffffff0000ffffff current block:00000001--Offset:00127--cnt bytes:40--data is:00000000000000000000000000000000000000000000000000000000000000000000000000000000 current block:00000002--Offset:00127--cnt bytes:40--data is:ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff current block:00000003--Offset:00127--cnt bytes:40--data is:000001cc6d090000002d5679ab00000d0c011039b4964991ed7c1f87d6324167616f70656e670000 current block:00000004--Offset:00127--cnt bytes:40--data is:00000000000000000000000000000000000000000000000000000000000000000000000000000000 current block:00000005--Offset:00127--cnt bytes:40--data is:00000000000000000000000000000000000000000000000000000000000000000000000000000000
