如何从SQL Server表对象生成类?
我说的不是使用ORM。我只需要创建实体(简单类)。喜欢的东西:
public class Person
{
public string Name { get;set; }
public string Phone { get;set; }
}
给定一个表，比如:
+----+-------+----------------+
| ID | Name | Phone |
+----+-------+----------------+
| 1 | Alice | (555) 555-5550 |
| 2 | Bob | (555) 555-5551 |
| 3 | Cathy | (555) 555-5552 |
+----+-------+----------------+
当前回答
如果你可以访问SQL Server 2016，你可以使用FOR JSON(包含INCLUDE_NULL_VALUES)选项从选择语句中获取JSON输出。复制输出，然后在Visual Studio中，粘贴special ->，粘贴JSON作为类。
算是预算上的解决方案，但可能会节省一些时间。
其他回答
我无法让亚历克斯的答案在Sql Server 2008 R2上工作。所以，我用同样的基本原理重写了它。它现在支持模式，并且对列属性映射(包括将可为空的日期类型映射为可为空的c#值类型)进行了一些修复。下面是Sql语句:
DECLARE @TableName VARCHAR(MAX) = 'NewsItem' -- Replace 'NewsItem' with your table name
DECLARE @TableSchema VARCHAR(MAX) = 'Markets' -- Replace 'Markets' with your schema name
DECLARE @result varchar(max) = ''
SET @result = @result + 'using System;' + CHAR(13) + CHAR(13)
IF (@TableSchema IS NOT NULL)
BEGIN
SET @result = @result + 'namespace ' + @TableSchema + CHAR(13) + '{' + CHAR(13)
END
SET @result = @result + 'public class ' + @TableName + CHAR(13) + '{' + CHAR(13)
SET @result = @result + '#region Instance Properties' + CHAR(13)
SELECT
@result = @result + CHAR(13)
+ ' public ' + ColumnType + ' ' + ColumnName + ' { get; set; } ' + CHAR(13)
FROM (SELECT
c.COLUMN_NAME AS ColumnName,
CASE c.DATA_TYPE
WHEN 'bigint' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'Int64?'
ELSE 'Int64'
END
WHEN 'binary' THEN 'Byte[]'
WHEN 'bit' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'bool?'
ELSE 'bool'
END
WHEN 'char' THEN 'string'
WHEN 'date' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'DateTime?'
ELSE 'DateTime'
END
WHEN 'datetime' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'DateTime?'
ELSE 'DateTime'
END
WHEN 'datetime2' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'DateTime?'
ELSE 'DateTime'
END
WHEN 'datetimeoffset' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'DateTimeOffset?'
ELSE 'DateTimeOffset'
END
WHEN 'decimal' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'decimal?'
ELSE 'decimal'
END
WHEN 'float' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'Single?'
ELSE 'Single'
END
WHEN 'image' THEN 'Byte[]'
WHEN 'int' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'int?'
ELSE 'int'
END
WHEN 'money' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'decimal?'
ELSE 'decimal'
END
WHEN 'nchar' THEN 'string'
WHEN 'ntext' THEN 'string'
WHEN 'numeric' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'decimal?'
ELSE 'decimal'
END
WHEN 'nvarchar' THEN 'string'
WHEN 'real' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'Double?'
ELSE 'Double'
END
WHEN 'smalldatetime' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'DateTime?'
ELSE 'DateTime'
END
WHEN 'smallint' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'Int16?'
ELSE 'Int16'
END
WHEN 'smallmoney' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'decimal?'
ELSE 'decimal'
END
WHEN 'text' THEN 'string'
WHEN 'time' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'TimeSpan?'
ELSE 'TimeSpan'
END
WHEN 'timestamp' THEN 'Byte[]'
WHEN 'tinyint' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'Byte?'
ELSE 'Byte'
END
WHEN 'uniqueidentifier' THEN CASE C.IS_NULLABLE
WHEN 'YES' THEN 'Guid?'
ELSE 'Guid'
END
WHEN 'varbinary' THEN 'Byte[]'
WHEN 'varchar' THEN 'string'
ELSE 'Object'
END AS ColumnType,
c.ORDINAL_POSITION
FROM INFORMATION_SCHEMA.COLUMNS c
WHERE c.TABLE_NAME = @TableName
AND ISNULL(@TableSchema, c.TABLE_SCHEMA) = c.TABLE_SCHEMA) t
ORDER BY t.ORDINAL_POSITION
SET @result = @result + CHAR(13) + '#endregion Instance Properties' + CHAR(13)
SET @result = @result + '}' + CHAR(13)
IF (@TableSchema IS NOT NULL)
BEGIN
SET @result = @result + CHAR(13) + '}'
END
PRINT @result
它生成的c#代码如下所示:
using System;
namespace Markets
{
public class NewsItem {
#region Instance Properties
public Int32 NewsItemID { get; set; }
public Int32? TextID { get; set; }
public String Description { get; set; }
#endregion Instance Properties
}
}
It may be an idea to use EF, Linq to Sql, or even Scaffolding; however, there are times when a piece of coding like this comes in handy. Frankly, I do not like using EF navigation properties where the code it generates made 19,200 separate database calls to populate a 1000 row grid. This could have been achieved in a single database call. Nonetheless, it could just be that your technical architect does not want you to use EF and the like. So, you have to revert to code like this... Incidentally, it may also be an idea to decorate each of the properties with attributes for DataAnnotations, etc., but I'm keeping this strictly POCO.
编辑 修正了时间戳和Guid?
要打印带有注释(摘要)的NULLABLE属性，使用这个。 这是对第一个答案的轻微修改
declare @TableName sysname = 'TableName'
declare @result varchar(max) = 'public class ' + @TableName + '
{'
select @result = @result
+ CASE WHEN ColumnDesc IS NOT NULL THEN '
/// <summary>
/// ' + ColumnDesc + '
/// </summary>' ELSE '' END
+ '
public ' + ColumnType + ' ' + ColumnName + ' { get; set; }'
from
(
select
replace(col.name, ' ', '_') ColumnName,
column_id,
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 + CASE WHEN col.is_nullable=1 AND typ.name NOT IN ('binary', 'varbinary', 'image', 'text', 'ntext', 'varchar', 'nvarchar', 'char', 'nchar') THEN '?' ELSE '' END ColumnType,
colDesc.colDesc AS ColumnDesc
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
OUTER APPLY (
SELECT TOP 1 CAST(value AS NVARCHAR(max)) AS colDesc
FROM
sys.extended_properties
WHERE
major_id = col.object_id
AND
minor_id = COLUMNPROPERTY(major_id, col.name, 'ColumnId')
) colDesc
where object_id = object_id(@TableName)
) t
order by column_id
set @result = @result + '
}'
print @result
我将几个基于SQL的答案(主要是Alex Aza的根答案)打包到kassify中，这是一个控制台应用程序，可以一次性为指定的数据库生成所有类:
例如，给定一个Users表，它是这样的:
+----+------------------+-----------+---------------------+
| Id | Name | Username | Email |
+----+------------------+-----------+---------------------+
| 1 | Leanne Graham | Bret | Sincere@april.biz |
| 2 | Ervin Howell | Antonette | Shanna@melissa.tv |
| 3 | Clementine Bauch | Samantha | Nathan@yesenia.net |
+----+------------------+-----------+---------------------+
klassify将生成一个名为Users.cs的文件，看起来像这样:
public class User
{
public int Id {get; set; }
public string Name { get;set; }
public string Username { get; set; }
public string Email { get; set; }
}
它将为每个表输出一个文件。丢弃你不用的东西。
使用
--out, -o:
output directory << defaults to the current directory >>
--user, -u:
sql server user id << required >>
--password, -p:
sql server password << required >>
--server, -s:
sql server << defaults to localhost >>
--database, -d:
sql database << required >>
--timeout, -t:
connection timeout << defaults to 30 >>
--help, -h:
show help
如果你可以访问SQL Server 2016，你可以使用FOR JSON(包含INCLUDE_NULL_VALUES)选项从选择语句中获取JSON输出。复制输出，然后在Visual Studio中，粘贴special ->，粘贴JSON作为类。
算是预算上的解决方案，但可能会节省一些时间。
你刚刚做了，只要你的表包含两列，并被称为'tblPeople'之类的东西。
您总是可以编写自己的SQL包装器。实际上我更喜欢这样做，我讨厌生成代码，以任何方式。
也许创建一个DAL类，并有一个名为GetPerson(int id)的方法，用于查询数据库中的person，然后从结果集中创建person对象。
