SQL子查询返回的值超过1

Question

嗨，我正在尝试执行查询以获取特定数字之间的行，就像我正在尝试获取10-20之间的行。 所以我正在使用子查询，以便我可以使用row_number()函数

查询失败，并显示以下错误：

SQL子查询返回的值超过1

所以我需要找出一个出路，因为我需要从查询中获得1个以上的结果

PROCEDURE dbo.Search

    (
    @search_text varchar(max), 
    @search_category varchar(max),
    @page int,
    @COUNT INT OUTPUT
    )

AS

     SET NOCOUNT ON
     DECLARE @Lower_limit int = (@page-1)*10;
     DECLARE @Upper_limit int = (@page * 10) + 1;
    -- SET @COUNT =0
     IF @search_category='deal'
     BEGIN
        SET @COUNT = (SELECT COUNT(*) FROM dealData WHERE dealInfo LIKE  '%' + @search_text + '%' OR dealName LIKE '%' + @search_text + '%' OR dealDescription LIKE  '%' + @search_text + '%' GROUP BY dealId);
        SELECT x.dealId , x.ROW 
        FROM
        ( SELECT dealId,ROW_NUMBER() OVER(ORDER BY dealId) as ROW from dealData WHERE dealInfo LIKE  '%' + @search_text + '%' OR dealName LIKE '%' + @search_text + '%' OR dealDescription LIKE  '%' + @search_text + '%'  GROUP BY dealId)x   
        WHERE x.ROW < @Upper_limit AND x.ROW > @Lower_limit
     END

这是完整的过程，当我尝试从以下代码调用它时，在_command.ExecuteReader（）;中出现异常。 Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

 _query = "Search";
                _command = new SqlCommand(_query, _connection);
                _command.CommandType = CommandType.StoredProcedure;
                _command.Parameters.AddWithValue("@search_text", search_text);
                _command.Parameters.AddWithValue("@search_category", search_category);
                _command.Parameters.AddWithValue("@page", page);
                var returnParameter = _command.Parameters.Add("@COUNT", SqlDbType.Int);
                returnParameter.Direction = ParameterDirection.Output;
                _reader = _command.ExecuteReader();
                while (_reader.Read())
                {
                    search_result index = new search_result();
                    index.category_id = this._categoryIdFromName(search_category);
                    index.post_id = _reader.GetValue(0).ToString();
                    _searchList.Add(index);
                }

Answer 1

问题是您的sp的这一部分：

SET @COUNT = (  SELECT COUNT(*) FROM dealData 
                WHERE dealInfo LIKE  '%' + @search_text + '%' 
                OR dealName LIKE '%' + @search_text + '%' 
                OR dealDescription LIKE  '%' + @search_text + '%' 
                GROUP BY dealId)

具体来说，是GROUP BY dealId部分。 如果该表上有多个dealId ，那么结果将是获得多行。 显然，您不能将其分配给标量变量。 需要将@Count声明为表变量（这将更改sp其余部分的逻辑），或者您摆脱了GROUP BY dealId ，并验证它是否可以提供所需的结果。

Answer 2

我必须同意@Lamak，并且仅发布答案，以便重复可能会影响知识。 如果您通过以下方式重新编写作业，则问题将消失：

SELECT @COUNT = COUNT(*) 
  FROM dbo.dealData 
  WHERE dealInfo        LIKE '%' + @search_text + '%' 
     OR dealName        LIKE '%' + @search_text + '%' 
     OR dealDescription LIKE '%' + @search_text + '%' 
  /* GROUP BY dealId */ -- there is NO REASON for this grouping if you want total count!
;

Answer 3

除了关于填充返回多行变量的子查询的其他人所说的以外，可能还有一种更有效的方法来获得您想要的内容（我假设是分页的）。 如注释中所述，这假定GroupId是DealData表的主键：

Declare @Results Table
    (
    DealId ... not null Primary Key
    , RowNumAsc int not null
    , TotalCount int not null
    );

With NumberedData As
        (
        Select DealId
            , Row_Number() Over ( Order By GroupId ) As RowNumAsc
            , Row_Number() Over ( Order By GroupId Desc ) As RowNumDesc
        From DealData
        Where dealInfo LIKE  '%' + @search_text + '%' 
            Or dealName LIKE '%' + @search_text + '%' 
            Or dealDescription LIKE  '%' + @search_text + '%'  
        )
Insert @Results( DealId, RowNumAsc, TotalCount )
Select DealId, RowNumAsc
    , Min( RowNumAsc + RowNumDesc - 1 ) As Count
From NumberedData
Where RowNumAsc < @UpperLimit
    And RowNumAsc >= @LowerLimit
Group By DealId 

Set @Count = ( Select TOP 1 TotalCount From @Results );
Select DealId, RowNumAsc
From @Results