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Sql Server 基本数据类型

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Jun 07, 2016 pm 05:42 PM

serverBasicdatatype

第一大类:整数数据 bit:bit数据类型代表0,1或NULL,就是表示true,false.占用1byte. int:以4个字节来存储正负数.可存储范围为:-2^31至2^31-1. smallint:以2个字节来存储正负数.存储范围为:-2^15至2^15-1 tinyint: 是最小的整数类型,仅用1字节,范围:0至此^8-1

第一大类:整数数据

bit:bit数据类型代表0,1或NULL,就是表示true,false.占用1byte.
int:以4个字节来存储正负数.可存储范围为:-2^31至2^31-1.
smallint:以2个字节来存储正负数.存储范围为:-2^15至2^15-1
tinyint: 是最小的整数类型,仅用1字节,范围:0至此^8-1

第二大类:精确数值数据

numeric:表示的数字可以达到38位,存储数据时所用的字节数目会随着使用权用位数的多少变化.
decimal:和numeric差不多

第三大类:近似浮点数值数据

float:用8个字节来存储数据.最多可为53位.范围为:-1.79E+308至1.79E+308.
real:位数为24,用4个字节,数字范围:-3.04E+38至3.04E+38

第四大类:日期时间数据

datatime:表示时间范围可以表示从1753/1/1至9999/12/31,时间可以表示到3.33/1000秒.使用8个字节.
smalldatetime:表示时间范围可以表示从1900/1/1至2079/12/31.使用4个字节.

第五大类:字符串数据

char:长度是设定的,最短为1字节,最长为8000个字节.不足的长度会用空白补上.
varchar:长度也是设定的,最短为1字节,最长为8000个字节,尾部的空白会去掉.
text:长宽也是设定的,最长可以存放2G的数据.

第六大类:Unincode字符串数据

nchar:长度是设定的,最短为1字节,最长为4000个字节.不足的长度会用空白补上.储存一个字符需要2个字节.
nvarchar:长度是设定的,最短为1字节,最长为4000个字节.尾部的空白会去掉.储存一个字符需要2个字节.
ntext:长度是设定的,最短为1字节,最长为2G.尾部的空白会去掉,储存一个字符需要2个字节.

第七大类:货币数据类型

money:记录金额范围为:-92233720368577.5808至92233720368577.5807.需要8 个字节.
smallmoney:记录金额范围为:-214748.3648至214748.36487.需要4个字节.

第八大类:标记数据

timestamp:该数据类型在每一个表中是唯一的!当表中的一个记录更改时,该记录的timestamp字段会自动更新.（注：只要一行中任意一个字段有修改，虚拟主机，该值就会变动。还是二进制类型的）
uniqueidentifier:用于识别数据库里面许多个表的唯一一个记录.

第九大类:二进制码字符串数据

binary:固定长度的二进制码字符串字段,最短为1,最长为8000.
varbinary:与binary差异为数据尾部是00时,varbinary会将其去掉
image:为可变长度的二进制码字符串,最长2G.

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