是否应该在此处使用表值参数？

Question

我有以下查询：

 @"UPDATE students SET IsDeleted = 1 WHERE StudentId IN (
         SELECT StudentId FROM Class where PassId IN (
              SELECT Id FROM ClassValueTable WHERE IsDeleted <> 1" 
                + activeIds)))";

其中activeIds =一些数字的字符串，例如：1,2,3,4 ...

我想将此查询转换为存储过程。我的问题是将activeIds作为参数传递给此存储过程的最佳方法是什么？

*代码在C＃中并且正在使用SQL Server 2008

Answer 1

是的，使用表值参数。首先创建一个类型：

CREATE TYPE dbo.StudentIDs(ID INT PRIMARY KEY);

现在您的过程可以使用此方法（请注意，我已将嵌套IN查询更改为适当的联接）：

CREATE PROCEDURE dbo.MarkStudentsAsDeleted
  @IDs dbo.StudentIDs READONLY
AS
BEGIN
  SET NOCOUNT ON;

  UPDATE s SET IsDeleted = 1
    FROM dbo.Students AS s
    INNER JOIN dbo.Class AS c
    ON s.StudentId = c.StudentId
    INNER JOIN dbo.ClassValueTable AS ct
    ON c.PassId = ct.Id
    WHERE ct.IsDeleted <> 1
    AND EXISTS (SELECT 1 FROM @IDs WHERE StudentID = s.StudentID);
END 
GO

您的C＃代码将传递到DataTable中，或者您组装了activeIds的集合，而不是用逗号分隔的列表。

CREATE TYPE dbo.StudentIDs(ID INT PRIMARY KEY);

如果要坚持将字符串传递到存储过程中，则需要使用split函数。例如：

CREATE FUNCTION dbo.SplitInts
(
   @List       VARCHAR(MAX),
   @Delimiter  VARCHAR(255) = ','
)
RETURNS TABLE
WITH SCHEMABINDING 
AS
  RETURN 
  (  
    SELECT [value] = y.i.value('(./text())[1]', 'int')
    FROM 
    ( 
      SELECT x = CONVERT(XML, '<i>' 
        + REPLACE(@List, @Delimiter, '</i><i>') 
        + '</i>').query('.')
    ) AS a CROSS APPLY x.nodes('i') AS y(i)
  );
GO

现在您的存储过程可以是：

CREATE PROCEDURE dbo.MarkStudentsAsDeleted
  @IDs VARCHAR(MAX)
AS
BEGIN
  SET NOCOUNT ON;

  UPDATE s SET IsDeleted = 1
    FROM dbo.Students AS s
    INNER JOIN dbo.Class AS c
    ON s.StudentId = c.StudentId
    INNER JOIN dbo.ClassValueTable AS ct
    ON c.PassId = ct.Id
    WHERE ct.IsDeleted <> 1
    AND EXISTS (SELECT 1 FROM dbo.SplitInts(@IDs, ',') WHERE Item = s.StudentID);
END 
GO