expression

Is an expression of type sql_variant.

property

Contains the name of the sql_variant property for which information is to be provided. property is varchar(128), and can be any one of the following values.

Value	Description	Base type of sql_variant returned
BaseType	SQL Server data type, such as: bigint binary char date datetime datetime2 datetimeoffset decimal float int money nchar numeric nvarchar real smalldatetime smallint smallmoney time tinyint uniqueidentifier varbinary varchar	sysname NULL = Input is not valid.
Precision	Number of digits of the numeric base data type: datetime = 23 smalldatetime = 16 float = 53 real = 24 decimal (p,s) and numeric (p,s) = p money = 19 smallmoney = 10 bigint = 19 int = 10 smallint = 5 tinyint = 3 bit = 1 All other types = 0	int NULL = Input is not valid.
Scale	Number of digits to the right of the decimal point of the numeric base data type: decimal (p,s) and numeric (p,s) = s money and smallmoney = 4 datetime = 3 all other types = 0	int NULL = Input is not valid.
TotalBytes	Number of bytes required to hold both the metadata and data of the value. This information would be useful in checking the maximum side of data in a sql_variant column. If the value is larger than 900, index creation will fail.	int NULL = Input is not valid.
Collation	Represents the collation of the particular sql_variant value.	sysname NULL = Input is not valid.
MaxLength	Maximum data type length, in bytes. For example, MaxLength of nvarchar(50) is 100, MaxLength of int is 4.	int NULL = Input is not valid.

sql_variant

The following example retrieves SQL_VARIANT_PROPERTY information about the colA value 46279.1 where colB =1689, given that tableA has colA that is of type sql_variant and colB.

CREATE   TABLE tableA(colA sql_variant, colB int)
INSERT INTO tableA values ( cast (46279.1 as decimal(8,2)), 1689)
SELECT   SQL_VARIANT_PROPERTY(colA,'BaseType') AS 'Base Type',
         SQL_VARIANT_PROPERTY(colA,'Precision') AS 'Precision',
         SQL_VARIANT_PROPERTY(colA,'Scale') AS 'Scale'
FROM      tableA
WHERE      colB = 1689

Here is the result set. Note that each of these three values is a sql_variant.

Base Type    Precision    Scale
---------    ---------    -----
decimal      8           2

(1 row(s) affected)

Reference