SQL Server Data Type Mappings

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 and later)
DateTime Date GetSqlDateTime Date GetDateTime
datetime DateTime DateTime GetSqlDateTime DateTime GetDateTime
datetime2

(SQL Server 2008 and later)
DateTime DateTime2 None DateTime2 GetDateTime
datetimeoffset

(SQL Server 2008 and later)
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 GetSqlMoney Decimal GetDecimal
sql_variant Object * Variant GetSqlValue * Object GetValue *
text String

Char[]
Text GetSqlString String GetString

GetChars
time

(SQL Server 2008 and later)
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 Data Types (Database Engine).

See Also

SQL Server Data Types and ADO.NET
SQL Server Binary and Large-Value Data
Data Type Mappings in ADO.NET
Configuring Parameters and Parameter Data Types
ADO.NET Managed Providers and DataSet Developer Center