34,590
社区成员
发帖
与我相关
我的任务
分享请高手帮帮忙。oracle中的number型数据是怎么存储的？
oracle中的number型数据是怎么存储的？
比如number（1）和number（2）在数据库中存储的字节数是多少？谢谢。
比如number（1）和number（2）在数据库中存储的字节数是多少？谢谢。
...全文
请发表友善的回复…
发表回复
Fxx 2000-12-18
- 打赏
- 举报
v_a number;在数据库中缺省长度为22
v_b number(n);在数据库中缺省长度为n
v_c number(n,m);在数据库中缺省长度为n,m位小数
v_b number(n);在数据库中缺省长度为n
v_c number(n,m);在数据库中缺省长度为n,m位小数
zheng 2000-12-18
- 打赏
- 举报
老兄，我看你的问题实在没人回答，只好帮你找资料了，是英文的，辛苦你了。
NUMBER
You use the NUMBER datatype to store fixed or floating-point Oracle numbers. You can specify precision and scale. The maximum precision of a NUMBER value is 38; the magnitude range is 1.0E-129 to 9.99E125. Scale can range from -84 to 127.
NUMBER values are stored in a variable-length format, starting with an exponent byte and followed by 19 mantissa bytes. The high-order bit of the exponent byte is a sign bit, which is set for positive numbers. The low-order 7 bits represent the magnitude.
The mantissa forms a 38-digit number with each byte representing 2 of the digits in a base-100 format. The sign of the mantissa is specified by the value of the first (left-most) byte. If greater than 101 then the mantissa is negative and the first digit of the mantissa is equal to the left-most byte minus 101.
On output, the host variable contains the number as represented internally by Oracle. To accommodate the largest possible number, the output host variable must be 21 bytes long. Only the bytes used to represent the number are returned. Oracle does not blank-pad or null-terminate the output value. If you need to know the length of the returned value, use the VARNUM datatype instead.
There is seldom a need to use this external datatype.
NUMBER
You use the NUMBER datatype to store fixed or floating-point Oracle numbers. You can specify precision and scale. The maximum precision of a NUMBER value is 38; the magnitude range is 1.0E-129 to 9.99E125. Scale can range from -84 to 127.
NUMBER values are stored in a variable-length format, starting with an exponent byte and followed by 19 mantissa bytes. The high-order bit of the exponent byte is a sign bit, which is set for positive numbers. The low-order 7 bits represent the magnitude.
The mantissa forms a 38-digit number with each byte representing 2 of the digits in a base-100 format. The sign of the mantissa is specified by the value of the first (left-most) byte. If greater than 101 then the mantissa is negative and the first digit of the mantissa is equal to the left-most byte minus 101.
On output, the host variable contains the number as represented internally by Oracle. To accommodate the largest possible number, the output host variable must be 21 bytes long. Only the bytes used to represent the number are returned. Oracle does not blank-pad or null-terminate the output value. If you need to know the length of the returned value, use the VARNUM datatype instead.
There is seldom a need to use this external datatype.
