C# Equivalent of SQL Server DataTypes

Question

For the following SQL Server datatypes, what would be the corresponding datatype in C#?

Exact Numerics

bigint
numeric
bit
smallint
decimal
smallmoney
int
tinyint
money

Approximate Numerics

float
real

Date and Time

date
datetimeoffset
datetime2
smalldatetime
datetime
time

Character Strings

char
varchar
text

Unicode Character Strings

nchar
nvarchar
ntext

Binary Strings

binary
varbinary
image

Other Data Types

cursor
timestamp
hierarchyid
uniqueidentifier
sql_variant
xml
table

(source: MSDN)

I think this is what you might be looking for: [Mapping CLR Parameter Data](http://msdn.microsoft.com/en-us/library/ms131092.aspx) — Andrew Hare, Jan 08 '09 at 18:54

score 1312 · Accepted Answer · edited Feb 16 '22 at 12:44

This is for SQL Server 2005. There are updated versions of the table for SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 and SQL Server 2014.

SQL Server Data Types and Their .NET Framework Equivalents

The following table lists Microsoft SQL Server data types, their equivalents in the common language runtime (CLR) for SQL Server in the System.Data.SqlTypes namespace, and their native CLR equivalents in the Microsoft .NET Framework.

SQL Server data type	CLR data type (SQL Server)	CLR data type (.NET Framework)
varbinary	SqlBytes, SqlBinary	Byte[]
binary	SqlBytes, SqlBinary	Byte[]
varbinary(1), binary(1)	SqlBytes, SqlBinary	byte, Byte[]
image	None	None
varchar	None	None
char	None	None
nvarchar(1), nchar(1)	SqlChars, SqlString	Char, String, Char[]
nvarchar	SqlChars, SqlString	String, Char[]
nchar	SqlChars, SqlString	String, Char[]
text	None	None
ntext	None	None
uniqueidentifier	SqlGuid	Guid
rowversion	None	Byte[]
bit	SqlBoolean	Boolean
tinyint	SqlByte	Byte
smallint	SqlInt16	Int16
int	SqlInt32	Int32
bigint	SqlInt64	Int64
smallmoney	SqlMoney	Decimal
money	SqlMoney	Decimal
numeric	SqlDecimal	Decimal
decimal	SqlDecimal	Decimal
real	SqlSingle	Single
float	SqlDouble	Double
smalldatetime	SqlDateTime	DateTime
datetime	SqlDateTime	DateTime
sql_variant	None	Object
User-defined type(UDT)	None	user-defined type
table	None	None
cursor	None	None
timestamp	None	None
xml	SqlXml	None

Which CLR data type (SQL Server) should be used for `short` in .Net framework ? — Yogesh Patel, Apr 13 '18 at 08:28
@yogeshpatel, `short` (https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/short) is equal to System.Int16 in this listing. So that would be smallint in SQL Server. — Örjan Jämte, Apr 16 '18 at 08:44
Important note: SQL data type "float" defaults to "float(54)" which converts to C# "double". HOWEVER, SQL datatype "float(24)" converts to C# "float" only. So if you don't need many digits of precision and want to improve performance/memory, use float(24) in SQL and types "float" in C#. — Jason, Feb 13 '21 at 00:37

score 93 · Answer 2 · answered Jan 17 '19 at 09:41

93

SQL Server and .Net Data Type mapping

answered Jan 17 '19 at 09:41

Must.Tek

1,220
10
17

score 17 · Answer 3 · edited Oct 16 '19 at 15:54

In case anybody is looking for methods to convert from/to C# and SQL Server formats, here goes a simple implementation:

private readonly string[] SqlServerTypes = { "bigint", "binary", "bit",  "char", "date",     "datetime", "datetime2", "datetimeoffset", "decimal", "filestream", "float",  "geography",                              "geometry",                              "hierarchyid",                              "image",  "int", "money",   "nchar",  "ntext",  "numeric", "nvarchar", "real",   "rowversion", "smalldatetime", "smallint", "smallmoney", "sql_variant", "text",   "time",     "timestamp", "tinyint", "uniqueidentifier", "varbinary", "varchar", "xml" };
private readonly string[] CSharpTypes    = { "long",   "byte[]", "bool", "char", "DateTime", "DateTime", "DateTime",  "DateTimeOffset", "decimal", "byte[]",     "double", "Microsoft.SqlServer.Types.SqlGeography", "Microsoft.SqlServer.Types.SqlGeometry", "Microsoft.SqlServer.Types.SqlHierarchyId", "byte[]", "int", "decimal", "string", "string", "decimal", "string",   "Single", "byte[]",     "DateTime",      "short",    "decimal",    "object",      "string", "TimeSpan", "byte[]",    "byte",    "Guid",             "byte[]",    "string",  "string" };

public string ConvertSqlServerFormatToCSharp(string typeName)
{
    var index = Array.IndexOf(SqlServerTypes, typeName);

    return index > -1
        ? CSharpTypes[index]
        : "object";
}

public string ConvertCSharpFormatToSqlServer(string typeName)
{
    var index = Array.IndexOf(CSharpTypes, typeName);

    return index > -1
        ? SqlServerTypes[index]
        : null;
}

Edit: fixed typo

Your method ConvertCSharpFormatToSqlServer will only always return the first instance found as CSharp Types are not unique, i.e. "byte[]" will always return "binary" even though it's mapped to 5 other Sql Server Types. — David, Sep 26 '20 at 08:17
@David although what you said is not technicaly wrong, it makes sense when you are using the `ConvertSqlServerFormatToCSharp` method. This is just an example, you can always modify it for your own needs. — AndreFeijo, Sep 28 '20 at 09:36

score 7 · Answer 4 · answered Mar 15 '17 at 07:54

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. Click Here's a link! for detail

https://msdn.microsoft.com/en-us/library/cc716729(v=vs.110).aspx

score 6 · Answer 5 · edited Jan 20 '21 at 17:15

public static string FromSqlType(string sqlTypeString)
{
    if (! Enum.TryParse(sqlTypeString, out Enums.SQLType typeCode))
    {
        throw new Exception("sql type not found");
    }
    switch (typeCode)
    {
        case Enums.SQLType.varbinary:
        case Enums.SQLType.binary:
        case Enums.SQLType.filestream:
        case Enums.SQLType.image:
        case Enums.SQLType.rowversion:
        case Enums.SQLType.timestamp://?
            return "byte[]";
        case Enums.SQLType.tinyint:
            return "byte";
        case Enums.SQLType.varchar:
        case Enums.SQLType.nvarchar:
        case Enums.SQLType.nchar:
        case Enums.SQLType.text:
        case Enums.SQLType.ntext:
        case Enums.SQLType.xml:
            return "string";
        case Enums.SQLType.@char:
            return "char";
        case Enums.SQLType.bigint:
            return "long";
        case Enums.SQLType.bit:
            return "bool";
        case Enums.SQLType.smalldatetime:
        case Enums.SQLType.datetime:
        case Enums.SQLType.date:
        case Enums.SQLType.datetime2:
            return "DateTime";
        case Enums.SQLType.datetimeoffset:
            return "DateTimeOffset";
        case Enums.SQLType.@decimal:
        case Enums.SQLType.money:
        case Enums.SQLType.numeric:
        case Enums.SQLType.smallmoney:
            return "decimal";
        case Enums.SQLType.@float:
            return "double";
        case Enums.SQLType.@int:
            return "int";
        case Enums.SQLType.real:
            return "Single";
        case Enums.SQLType.smallint:
            return "short";
        case Enums.SQLType.uniqueidentifier:
            return "Guid";
        case Enums.SQLType.sql_variant:
            return "object";
        case Enums.SQLType.time:
            return "TimeSpan";
        default:
            throw new Exception("none equal type");
    }
}

public enum SQLType
{
    varbinary,//(1)
    binary,//(1)
    image,
    varchar,
    @char,
    nvarchar,//(1)
    nchar,//(1)
    text,
    ntext,
    uniqueidentifier,
    rowversion,
    bit,
    tinyint,
    smallint,
    @int,
    bigint,
    smallmoney,
    money,
    numeric,
    @decimal,
    real,
    @float,
    smalldatetime,
    datetime,
    sql_variant,
    table,
    cursor,
    timestamp,
    xml,
    date,
    datetime2,
    datetimeoffset,
    filestream,
    time,
}

C# Equivalent of SQL Server DataTypes

5 Answers5

SQL Server Data Types and Their .NET Framework Equivalents

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