Mapping SQL Server Data Types to C# Equivalents

When working with databases and programming languages, it’s essential to understand how data types are mapped between the two. In this tutorial, we’ll explore the mapping of SQL Server data types to their equivalent C# data types.

SQL Server provides a wide range of data types to store various types of data, including numeric, character, date, and binary data. Similarly, C# has its own set of data types that can be used to represent different types of data. To ensure seamless interaction between SQL Server and C#, it’s crucial to understand the mapping between these data types.

Exact Numerics

The following SQL Server data types are considered exact numerics:

• bigint
• numeric
• bit
• smallint
• decimal
• smallmoney
• int
• tinyint
• money

Their equivalent C# data types are:

• long (for bigint)
• decimal (for numeric, decimal, and money)
• bool (for bit)
• short (for smallint)
• int (for int)
• byte (for tinyint)

Approximate Numerics

The following SQL Server data types are considered approximate numerics:

• float
• real

Their equivalent C# data types are:

• double (for float)
• float (for real)

Date and Time

The following SQL Server data types are used to store date and time values:

• date
• datetimeoffset
• datetime2
• smalldatetime
• datetime
• time

Their equivalent C# data types are:

• DateTime (for date, datetime, and smalldatetime)
• DateTimeOffset (for datetimeoffset)
• TimeSpan (for time)

Character Strings

The following SQL Server data types are used to store character strings:

• char
• varchar
• text

Their equivalent C# data types are:

• char (for char)
• string (for varchar and text)

Unicode Character Strings

The following SQL Server data types are used to store Unicode character strings:

• nchar
• nvarchar
• ntext

Their equivalent C# data types are:

• string (for nchar, nvarchar, and ntext)

Binary Strings

The following SQL Server data types are used to store binary strings:

• binary
• varbinary
• image

Their equivalent C# data types are:

• byte[] (for binary, varbinary, and image)

Other Data Types

The following SQL Server data types do not have direct equivalents in C#:

• cursor
• timestamp
• hierarchyid
• uniqueidentifier (although it can be represented as a Guid in C#)
• sql_variant (which can be represented as an object in C#)

Example Use Cases

To demonstrate the mapping of SQL Server data types to C#, let’s consider the following example:

using System;
using System.Data;

class Program
{
    static void Main()
    {
        // Create a sample DataTable with various data types
        DataTable table = new DataTable();
        table.Columns.Add("ID", typeof(int));
        table.Columns.Add("Name", typeof(string));
        table.Columns.Add("DateOfBirth", typeof(DateTime));
        table.Columns.Add("Salary", typeof(decimal));

        // Add some sample data to the DataTable
        table.Rows.Add(1, "John Doe", DateTime.Parse("1990-01-01"), 50000.00m);
        table.Rows.Add(2, "Jane Smith", DateTime.Parse("1995-06-15"), 60000.00m);

        // Print the data to the console
        foreach (DataRow row in table.Rows)
        {
            Console.WriteLine($"ID: {row["ID"]}, Name: {row["Name"]}, Date of Birth: {row["DateOfBirth"]}, Salary: {row["Salary"]}");
        }
    }
}

In this example, we create a DataTable with columns representing different SQL Server data types (int, varchar, datetime, and decimal). We then add some sample data to the table and print it to the console using C#.

Conclusion

In conclusion, understanding the mapping of SQL Server data types to their equivalent C# data types is essential for working with databases and programming languages. By knowing the correct mappings, you can ensure seamless interaction between SQL Server and C#, and write more efficient and effective code.