[SQL Server CLR] CLR表值函数

注：
其他还有，CLR标量函数和聚合函数

1. C#创建dll

public class UserDefinedFunctions
{
    [SqlFunction(
        DataAccess = DataAccessKind.Read,
        FillRowMethodName = "FillRow",    //需要指定填充方法
        IsDeterministic = true)]
    public static IEnumerable Parse(SqlString str)
    {
        return new List<Item>
        {
            new Item
            {
                Key = "1",
                Value = "2"
            },
            new Item
            {
                Key = "3",
                Value = "4"
            } 
        };
    }

    public class Item
    {
        public SqlString Key { get; set; }

        public SqlString Value { get; set; }
    }

    public static void FillRow(object obj,
                       out SqlString key,
                       out SqlString value)
    {
        Item item = obj as Item;

        key = item.Key;
        value = item.Value;
    }
};

2. Sql Server配置

--启用CLR
EXEC sp_configure 'clr enabled', 1    
RECONFIGURE

--指定数据库
USE  TestDatabase
GO

--创建assembly
CREATE ASSEMBLY [Parser] FROM 'D:\temp\ClassLibrary1.dll'    
GO

--创建function
CREATE FUNCTION func_Parse(@str nvarchar(32))     
    RETURNS TABLE([Key] nvarchar(32),[Value] nvarchar(32)) 
    AS EXTERNAL NAME [Parser].[UserDefinedFunctions].[Parse]

3. 调用

SELECT * FROM [dbo].[func_Parse]('123')