SQL Server Data type

Text type:

Char: fixed -length non- Unicode character data with a maximum length of 8,000 characters

VARCHAR: variable -length non- Unicode character data with a maximum length of 8,000 characters

Text: Store long text messages with a maximum length of 231-1 (2147483647) characters

NCHAR: fixed-length Unicode character data with a maximum length of 4,000 characters

NVARCHAR: variable-length Unicode character data with a maximum length of 4,000 characters

ntext: Storing long text messages up to 230-1 (1073741823) characters in length

Unicode is a character encoding scheme developed by international organizations that can accommodate all the words and symbols in the world.

The data type with n is twice times the length without n. For example, nchar (1) and char (2) are the same length

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Integer type:

int: occupies 4 bytes, can represent range: 2131 ~231-1 integer

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Exact number type:

Decimal:-1038 ~1038-1 between fixed precision and fractional numbers

Numeric: function equivalent to demical

notation: decimal (integers, decimals) and numeric (integers, decimals)

Default: If you do not specify a number of digits, the default 18-bit integer, 0-bit decimal

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Date Type:

DateTime: Allowable range 1753-1-1 to 9999-1-1

smalldatetime: Permissible range 1900-1-1 to 2079-6-6

Time accuracy: datetime is accurate to 3/100 seconds; smalldatetime accurate to one minute

Appropriate description: 2013-08-20

Note: the date needs to be enclosed in single quotation marks (') when used

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Bit type:

Bit: Indicates "yes/no" type data. (0,1/true,false)

SQL Server Data type