SQL Server Data Type Mappings (ADO.NET)

Article
10/26/2011

SQL Server and the .NET Framework are based on different type systems. For example, the .NET Framework Decimal structure has a maximum scale of 28, whereas the SQL Server decimal and numeric data types have a maximum scale of 38. To maintain data integrity when reading and writing data, the SqlDataReader exposes SQL Server–specific typed accessor methods that return objects of System.Data.SqlTypes as well as accessor methods that return .NET Framework types. Both SQL Server types and .NET Framework types are also represented by enumerations in the DbType and SqlDbType classes, which you can use when specifying SqlParameter data types.

The following table shows the inferred .NET Framework type, the DbType and SqlDbType enumerations, and the accessor methods for the SqlDataReader.

SQL Server Database Engine type	.NET Framework type	SqlDbType enumeration	SqlDataReader SqlTypes typed accessor	DbType enumeration	SqlDataReader DbType typed accessor
bigint	Int64	BigInt	GetSqlInt64	Int64	GetInt64
binary	Byte[]	VarBinary	GetSqlBinary	Binary	GetBytes
bit	Boolean	Bit	GetSqlBoolean	Boolean	GetBoolean
char	String Char[]	Char	GetSqlString	AnsiStringFixedLength, String	GetString GetChars
date (SQL Server 2008 only)	DateTime	Date	GetSqlDateTime	Date	GetDateTime
datetime	DateTime	DateTime	GetSqlDateTime	DateTime	GetDateTime
datetime (SQL Server 2008 only)	DateTime	DateTime2	None	DateTime2	GetDateTime
datetimeoffset (SQL Server 2008 only)	DateTimeOffset	DateTimeOffset	none	DateTimeOffset	GetDateTimeOffset
decimal	Decimal	Decimal	GetSqlDecimal	Decimal	GetDecimal
FILESTREAM attribute (varbinary(max)	Byte[]	VarBinary	GetSqlBytes	Binary	GetBytes
float	Double	Float	GetSqlDouble	Double	GetDouble
image	Byte[]	Binary	GetSqlBinary	Binary	GetBytes
int	Int32	Int	GetSqlInt32	Int32	GetInt32
money	Decimal	Money	GetSqlMoney	Decimal	GetDecimal
nchar	String Char[]	NChar	GetSqlString	StringFixedLength	GetString GetChars
ntext	String Char[]	NText	GetSqlString	String	GetString GetChars
numeric	Decimal	Decimal	GetSqlDecimal	Decimal	GetDecimal
nvarchar	String Char[]	NVarChar	GetSqlString	String	GetString GetChars
real	Single	Real	GetSqlSingle	Single	GetFloat
rowversion	Byte[]	Timestamp	GetSqlBinary	Binary	GetBytes
smalldatetime	DateTime	DateTime	GetSqlDateTime	DateTime	GetDateTime
smallint	Int16	SmallInt	GetSqlInt16	Int16	GetInt16
smallmoney	Decimal	SmallMoney	GetSqlDecimal	Decimal	GetDecimal
sql_variant	Object *	Variant	GetSqlValue *	Object	GetValue *
text	String Char[]	Text	GetSqlString	String	GetString GetChars
time (SQL Server 2008 only)	TimeSpan	Time	none	Time	GetDateTime
timestamp	Byte[]	Timestamp	GetSqlBinary	Binary	GetBytes
tinyint	Byte	TinyInt	GetSqlByte	Byte	GetByte
uniqueidentifier	Guid	UniqueIdentifier	GetSqlGuid	Guid	GetGuid
varbinary	Byte[]	VarBinary	GetSqlBinary	Binary	GetBytes
varchar	String Char[]	VarChar	GetSqlString	AnsiString, String	GetString GetChars
xml	Xml	Xml	GetSqlXml	Xml	none

* Use a specific typed accessor if you know the underlying type of the sql_variant.

SQL Server Books Online Reference

For more information about SQL Server data types, see the version of SQL Server Books Online for the version of SQL Server you are using.

SQL Server 2000	SQL Server 2005	SQL Server 2008
Data Types	Data Types (Database Engine)	Data Types (Database Engine)

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SQL Server Data Type Mappings (ADO.NET)

SQL Server Books Online Reference

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