SQL SERVER 表转化为C#实体（SQL 代码）

本文推出SqlServer表转化为实体的sql代码

在VS中有可以自带生成实体类的快捷操作，但是生成的代码比较杂乱，很多东西都是不需要的，一个一个去敲又很浪费时间，关键太无聊了

在闲暇之余写一份代码供大家学习，废话不多说，直接整干货：

DECLARE @TableName sysname = '[dbo].[Orders]';-- 要生成实体类的表名
DECLARE @Result VARCHAR(MAX) = 'public class ' + @TableName + '
{';
SELECT @Result = @Result + '
    /// <summary>
    /// '        + CAST(t.Summary AS VARCHAR(MAX)) + '
    /// </summary>
    public '     + ColumnType + NullableSign + ' ' + ColumnName + ' { get; set; }
'
FROM
(
    SELECT REPLACE(col.name, ' ', '_') ColumnName,
           col.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
                   'float'
               WHEN 'image' THEN
                   'byte[]'
               WHEN 'int' THEN
                   'int'
               WHEN 'money' THEN
                   'decimal'
               WHEN 'nchar' THEN
                   'char'
               WHEN 'ntext' THEN
                   'string'
               WHEN 'numeric' THEN
                   'decimal'
               WHEN 'nvarchar' THEN
                   'string'
               WHEN 'real' THEN
                   'double'
               WHEN 'smalldatetime' THEN
                   'DateTime'
               WHEN 'smallint' THEN
                   'short'
               WHEN 'smallmoney' THEN
                   'decimal'
               WHEN 'text' THEN
                   'string'
               WHEN 'time' THEN
                   'TimeSpan'
               WHEN 'timestamp' THEN
                   'DateTime'
               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,
           ISNULL(ep.value, col.name) AS Summary
    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
        LEFT JOIN sys.extended_properties ep
            ON ep.major_id = col.object_id
               AND ep.minor_id = col.column_id
    WHERE col.object_id = OBJECT_ID(@TableName)
) t
ORDER BY ColumnId;
SET @Result = @Result + '
}';
PRINT @Result;