Default common data types for SQL tables

Classification	Field type	Describe
Integer	Bit	Integer numbers of 0 or 1
	Int	Integer numbers from -2^31 (-2,147,483,648) to 2^31-1 (2,147,483,647)
	smallint	Integer numbers from -2^15 (-32,768) to 2^15-1 (32,767)
	tinyint	Integer numbers from 0 to 255
Exact decimals	Decimal (P,s)	Precision and number of effective digits from -10^38 to 10^38-1 p-width s
	Numeric (P,s)	Synonyms for decimal
Approximate decimals	Float	Variable-precision numbers from -1.79E+308 to 1.79E+308
	Real	Variable-precision numbers from -3.04E+38 to 3.04E+38
Currency	Money	Currency data from -2^63 ( -922,337,203,685,477.5808) to 2^63-1 (922,337,203,685,477.5807), Minimum currency unit 10 per thousand, Width 4
	SmallMoney	Currency data from -214,748.3648 to 214,748.3647, Minimum currency unit 10 per thousand, Width 4
Date Time	Datetime	Date and time data from January 1, 1753 to 9999 12th 31, The minimum time unit is 3% seconds or 3.33 milliseconds
	smalldatetime	Date and time data from January 1, 1900 to June 6, 2079, Minimum time unit is minutes
Special data types	Timestamp	Timestamp, unique number of a database width
	Cursor	A reference to a cursor
	uniqueidentifier	Global Unique identifier GUID
Character data	Char	Fixed-length non-Unicode character data with a maximum length of 8000
	varchar	Variable length non-Unicode character data up to a maximum of 8000
	Text	Variable length non-Unicode character data with a maximum length of 2^31-1 (2G)
Unicode	NChar	Fixed-length Unicode character data with a maximum length of 8000
	nvarchar	Variable-length Unicode character data up to a maximum of 8000
	ntext	Variable length Unicode character data with a maximum length of 2^31-1 (2G)
Binary data	Binary	Fixed-length binary data with a maximum length of 8000
	varbinary	Variable length binary data with a maximum length of 8000
	Image	Variable-length binary data with a maximum length of 2^31-1 (2G)

Note

1) For numeric data types, the width (scale) refers to the number of digits that are stored after the decimal point, and the precision (precision) is the number of digits that can be stored that contains the decimal point.
2) The storage width of money and small money is 4.
3) The timestamp column value is automatically updated when each row is updated, and the timestamp column cannot be part of the keyword or keyword.

4) Additional user-defined data types

(NET pick)

Default common data types for SQL tables