SQL：搜索空日期答案

【问题标题】：SQL: search for null dateSQL：搜索空日期
【发布时间】：2014-03-26 18:51:28
【问题描述】：

我有一个搜索我的成员表的选择过程。成员表有：

ID – Name –  Deleted
 1 – Marcus – NULL
 2 – Regina – 2014-03-26 09:33:00.000

存在：ID 一个 PK int no NULL，命名一个 varchar(250) 并删除了一个 datetime NULL。

这是我的程序：

CREATE PROCEDURE dbo.SELECT_MEMBERS

    @ID int = NULL,
    @Name varchar(250)= NULL,
    @Deleted datetime =NULL

AS
BEGIN
 IF @Deleted = ''
        BEGIN
            SET @Deleted = NULL
        END     
        ELSE 
        BEGIN
            SET @Deleted = @Deleted
        END

 SET NOCOUNT ON;

    SELECT  ID, Name, Deleted 
    FROM dbo.Members WHERE
       (@ID IS NULL OR @ID = ID)
   AND (@Name IS NULL OR @Name = Name)
   AND (@Deleted IS NULL OR @Deleted = Deleted)


END
GO

为了搜索没有删除日期的成员（如果他们有删除日期意味着他们不是活跃成员）我这样做：

EXEC dbo.SELECT_MEMBERS  @Deleted = ''

但这不起作用，因为我插入了已删除日期的行。

我做错了什么？

非常感谢！！

【问题讨论】：

标签： sql sql-server datetime select null

【解决方案1】：

CREATE PROCEDURE dbo.SELECT_MEMBERS

    @ID int = NULL,
    @Name varchar(250)= NULL,
    @Deleted datetime =NULL

AS
BEGIN

 SET NOCOUNT ON;

    SELECT  ID, Name, Deleted 
    FROM dbo.Members 
    WHERE ID = ID
    AND ISNULL(@Name, '') = ISNULL(Name, '')
    AND ISNULL(@Deleted, '') = ISNULL(Deleted, '')


END
GO

【讨论】：

【解决方案2】：

您似乎希望@Deleted 日期的空/NULL 值与NULL 值@ID 和@Name 的行为不同：您希望@Deleted 的实际比较为真仅当值为NULL 时。

我想你想要这样的东西：

CREATE PROCEDURE dbo.SELECT_MEMBERS
    @ID int = NULL,
    @Name varchar(250)= NULL,
    @Deleted datetime = NULL
AS
BEGIN
   SELECT ID, Name, Deleted 
   FROM dbo.Members
   WHERE (@ID IS NULL OR @ID = ID) AND
         (@Name IS NULL OR @Name = Name) AND
         ((@Deleted IS NULL  OR @Deleted = Deleted or @Deleted = '' and Deleted is null)
END;

【讨论】：