How Can I Generate C# Classes from SQL Server Tables?

Generating Classes from SQL Server Tables

Generating classes from database tables can streamline data access and provide a tangible representation of the data structure. This article explores a simple method to create entities as straightforward classes.

Creating the Entities

Let's consider a table named "Person" with the following schema:

+----+-------+----------------+
| ID | Name  |     Phone      |
+----+-------+----------------+
| 1 | Alice | (555) 555-5550 |
| 2 | Bob   | (555) 555-5551 |
| 3 | Cathy | (555) 555-5552 |
+----+-------+----------------+

To generate the corresponding class, we can utilize the following SQL script:

set @TableName sysname = 'TableName'
declare @Result varchar(max) = 'public class ' + @TableName + '
{'

select @Result = @Result + '
    public ' + ColumnType + NullableSign + ' ' + ColumnName + ' { get; set; }
'
from
(
    select 
        replace(col.name, ' ', '_') ColumnName,
        column_id ColumnId,
        case typ.name 
            when 'bigint' then 'long'
            when 'binary' then 'byte[]'
            when 'bit' then 'bool'
            when 'char' then 'string'
            when 'date' then 'DateTime'
            when 'datetime' then 'DateTime'
            when 'datetime2' then 'DateTime'
            when 'datetimeoffset' then 'DateTimeOffset'
            when 'decimal' then 'decimal'
            when 'float' then 'double'
            when 'image' then 'byte[]'
            when 'int' then 'int'
            when 'money' then 'decimal'
            when 'nchar' then 'string'
            when 'ntext' then 'string'
            when 'numeric' then 'decimal'
            when 'nvarchar' then 'string'
            when 'real' then 'float'
            when 'smalldatetime' then 'DateTime'
            when 'smallint' then 'short'
            when 'smallmoney' then 'decimal'
            when 'text' then 'string'
            when 'time' then 'TimeSpan'
            when 'timestamp' then 'long'
            when 'tinyint' then 'byte'
            when 'uniqueidentifier' then 'Guid'
            when 'varbinary' then 'byte[]'
            when 'varchar' then 'string'
            else 'UNKNOWN_' + typ.name
        end ColumnType,
        case 
            when col.is_nullable = 1 and typ.name in ('bigint', 'bit', 'date', 'datetime', 'datetime2', 'datetimeoffset', 'decimal', 'float', 'int', 'money', 'numeric', 'real', 'smalldatetime', 'smallint', 'smallmoney', 'time', 'tinyint', 'uniqueidentifier') 
            then '?' 
            else '' 
        end NullableSign
    from sys.columns col
        join sys.types typ on
            col.system_type_id = typ.system_type_id AND col.user_type_id = typ.user_type_id
    where object_id = object_id(@TableName)
) t
order by ColumnId

set @Result = @Result  + '
}'

print @Result

By executing this script, you will obtain the corresponding class definition for the "Person" table, which can then be utilized within your applications.

This approach gives you control over the generated class, ensuring that it meets the specific requirements of your project.

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