📅 最后修改于: 2020-12-02 01:50:23 🧑 作者: Mango
数据类型可以分为三种类型：
| Data Type | Description |
|---|---|
| char(n) | It is a fixed width character string. It can store maximum 8,000 characters. |
| varchar(n) | It is a variable width character string. It can store maximum 8,000 characters. |
| varchar(max) | It is a variable width character string. It can store maximum 1,073,741,824 characters. |
| text | It is a variable width character string. It can store maximum 2GB of text data. |
| nchar | It is a fixed width unicode string. It can store maximum 4,000 characters. |
| nvarchar | It is a variable width unicode string. It can store maximum 4,000 characters. |
| nvarchar(max) | It is a variable width unicode string. It can store maximum 536,870,912 characters. |
| ntext | It is a variable width unicode string. It can store maximum 2GB of text data. |
| bit | It allows 0, 1, or NULL values. |
| binary(n) | It is a fixed width binary string. It can store maximum 8,000 bytes |
| varbinary | It is a variable width binary string. It can store maximum 8,000 bytes |
| varbinary(max) | It is a variable width binary string. It can store maximum 2GB. |
| image | It is a variable width binary string. It can store maximum 2GB. |
| data type | description | storage |
|---|---|---|
| tinyint | allows whole numbers from 0 to 255 | 1 byte |
| smallint | allows whole numbers between -32,768 and 32,767 | 2 bytes |
| int | allows whole numbers between -2,147,483,648 and 2,147,483,647 | 4 bytes |
| bigint | allows whole numbers between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,807 | 8 bytes |
| decimal(p,s) | fixed precision and scale numbers.allows numbers from -10^38 +1 to 10^38 ?1.the p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. default is 18.the s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. default value is 0 | 5-17 bytes |
| numeric(p,s) | fixed precision and scale numbers.allows numbers from -10^38 +1 to 10^38 ?1.the p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. default is 18.the s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. default value is 0 | 5-17 bytes |
| smallmoney | monetary data from -214,748.3648 to 214,748.3647 | 4 bytes |
| money | monetary data from -922,337,203,685,477.5808 to 922,337,203,685,477.5807 | 8 bytes |
| float(n) | floating precision number data from -1.79e + 308 to 1.79e + 308.the n parameter indicates whether the field should hold 4 or 8 bytes. float(24) holds a 4-byte field and float(53) holds an 8-byte field. default value of n is 53. | 4 or 8 bytes |
| real | floating precision number data from -3.40e + 38 to 3.40e + 38 | 4 bytes |
| Data Type | Description | Storage |
|---|---|---|
| datetime | It specifies a date and time from january 1, 1753 to december 31, 9999 with an accuracy of 3.33 milliseconds. | 8 bytes |
| datetime2 | It specifies a date and time from january 1, 0001 to december 31, 9999 with an accuracy of 100 nanoseconds. | 6-8 bytes |
| smalldatetime | It specifies a date and time from january 1, 1900 to june 6, 2079 with an accuracy of 1 minute. | 4 bytes |
| date | It is used to store a date only. It specifies a date from january 1, 0001 to december 31, 9999. | 3 bytes |
| time | It is used to store a time only to an accuracy of 100 nanoseconds. | 3-5 bytes |
| datetimeoffset | It is the same as datetime2 with the addition of a time zone offset. | 8-10 bytes |
| timestamp | It stores a unique number that gets updated every time a row gets created or modified. the timestamp value is based upon an internal clock and does not correspond to real time. each table may have only one timestamp variable. |