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

抓取QueryFirst, visual studio扩展,从SQL查询生成包装类。你不仅得到…

public class MyClass{
    public string MyProp{get;set;}
    public int MyNumberProp{get;set;}
    ...
}

作为奖励,它还会……

public class MyQuery{
    public static IEnumerable<MyClass>Execute(){}
    public static MyClass GetOne(){}
    ...
}

您确定要将类直接基于表吗?表是属于DB的静态规范化数据存储概念。类是动态的、流动的、一次性的、特定于上下文的,也许是非规范化的。为什么不为您想要的操作数据编写真正的查询,然后让QueryFirst从中生成类呢?

其他回答

商业化,但codessmith Generator做到了:http://www.codesmithtools.com/product/generator

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?

从Postgres DB生成

DO $$ DECLARE v_tabela varchar; DECLARE v_cursor_colunas record; DECLARE v_nome_coluna varchar; DECLARE v_classe VARCHAR; DECLARE v_tipo VARCHAR; DECLARE v_schema_name VARCHAR; BEGIN v_schema_name := 'my-schema'; v_tabela := 'my-table'; select table_name INTO v_tabela from information_schema.tables where table_schema = v_schema_name and table_type = 'BASE TABLE' and table_name = v_tabela; v_classe := E'\r\n' || 'public class ' || v_tabela || ' {' || E'\r\n'; FOR v_cursor_colunas IN SELECT column_name as coluna, is_nullable as isnull, data_type as tipo, character_maximum_length as tamanho FROM information_schema.columns WHERE table_schema = v_schema_name AND table_name = v_tabela LOOP IF v_cursor_colunas.tipo='character varying' THEN v_tipo:= 'string'; ELSIF v_cursor_colunas.tipo='character' and v_cursor_colunas.tamanho=1 THEN v_tipo:= 'char'; ELSIF v_cursor_colunas.tipo='character' and v_cursor_colunas.tamanho<>1 THEN v_tipo:= 'string'; ELSIF v_cursor_colunas.tipo like 'timestamp%' THEN v_tipo:= 'DateTime'; IF v_cursor_colunas.isnull='YES' then v_tipo:= 'DateTime?'; END IF; ELSIF v_cursor_colunas.tipo='boolean' THEN v_tipo:= 'bool'; IF v_cursor_colunas.isnull='YES' then v_tipo:= 'bool?'; END IF; ELSIF v_cursor_colunas.tipo='integer' THEN v_tipo:= 'int'; IF v_cursor_colunas.isnull='YES' then v_tipo:= 'int?'; END IF; ELSIF v_cursor_colunas.tipo='numeric' THEN v_tipo:= 'double'; IF v_cursor_colunas.isnull='YES' then v_tipo:= 'double?'; END IF; ELSIF v_cursor_colunas.tipo='text' THEN v_tipo:= 'string'; ELSE v_tipo:= 'another'; END IF; v_nome_coluna := v_cursor_colunas.coluna; v_classe := v_classe || 'public ' || v_tipo || ' ' || v_cursor_colunas.coluna || ' { get; set; }' || E'\r\n'; END LOOP;

v_class:= v_class || E'\r\n' || '}'; RAISE NOTICE '%', v_class; $ $;

我很困惑你想要从这里得到什么,但这里是在设计你想要设计的东西时的一般选择。

在Visual Studio版本中使用内置的ORM。 自己编写一个,类似于您的代码示例。通常情况下,如果你不确定怎么做,教程是你最好的朋友。 使用另一种ORM,如NHibernate。

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。