Question

我有一个使用NHibernate标准查询机制动态编译的搜索查询。生成的SQL查询可能如下所示：

select 
    *
from
    sometable
where
(
    (
        firstname like 'chris%' or
        lastname like 'chris%'
    )
    and
    (
        firstname like 'vann%' or
        lastname like 'vann%'
    )    
)

表格中的数据可能如下所示：

FirstName         LastName
------------------------------
Chris             Smith
John              Vann
Chris             Vann

我想订购结果，使得匹配where子句中的两个子子句的行（即firstname = Chris和lastname = Vann）的排名高于仅匹配其中一个子子句的行。这在标准SQL中是否可行？

编辑：我大大简化了问题，以深入了解问题的核心。

Answer 1

这只是一个重要的开始。您可以创建计算priority列并按此列对行进行排序。该列是井匹配行的指示符。这里有一个示例代码：

create table #t (f varchar(10), l varchar(10) );

insert into #t values ('aa','ee'),('aa','ii'),('oo','ee');

select 
   *,
   case when f like 'aa%' then 1 else 0 end +
   case when l like 'aa%' then 1 else 0 end +
   case when f like 'ii%' then 1 else 0 end + 
   case when l like 'aa%' then 1 else 0 end 
   as priority
from #t
order by 
   priority desc

结果：

f  l  priority 
-- -- -------- 
aa ee 4        
aa ii 4        
oo ee 0

对于您的架构可能类似于：

select 
    *.
    case when firstname like 'chris%' and lastname like 'vann%' then 4 else 0 +
    case when firstname like 'chris%' and lastname not like 'vann%' then 3 else 0 +
    case when firstname not like 'chris%' and lastname like 'vann%' then 3 else 0 +
    ...
    as priority
from
    sometable
where
(
    (
        firstname like 'chris%' or
        lastname like 'chris%'
    )
    and
    (
        firstname like 'vann%' or
        lastname like 'vann%'
    )    
)
order by priority desc

Answer 2

这是我鼓吹的T-SQL排名，看起来效果不错。

使用差值功能对每个搜索对（姓，名，姓，名，姓，名，姓）进行排序，然后在名字或姓氏中搜索词的子字符串匹配时增加权重-第一个和最后一个比赛加权重。
按具有完全匹配的子字符串的顺序排序，然后按最早的匹配顺序排序，然后使搜索字符串的长度与名字/姓氏的长度之间的差最小。
TotalRank中的加权因子（* 2，* 4）是任意的，只反映了我希望对更重的比赛（第一至最后）进行加权的愿望。
下面的SQL有很多额外的列，它们说明了TotalRank列中的组件。您显然可以删除它们。

`

DECLARE @searchFirst varchar(max) = 'chris';

DECLARE @searchLast varchar(max) = 'vann';

SELECT firstname, lastname,

SOUNDEX(@searchFirst) as FSearchSoundEx,

SOUNDEX(firstname) as FSoundEx,

DIFFERENCE(firstname, @searchFirst) as FDiff,

LEN(firstName) - LEN(@searchFirst) as FFDelta,


SOUNDEX(lastname) as LSoundEx,

SOUNDEX(@searchLast) as LSearchSoundEx,

DIFFERENCE(lastName, @searchLast) as LDiff,

LEN(lastName) - LEN(@searchLast) as LLDelta,


PATINDEX('%' + @searchFirst + '%', firstname) as FFIndex,

PATINDEX('%' + @searchFirst + '%', lastname) as FLIndex,

PATINDEX('%' + @searchLast + '%', firstname) as LFIndex,

PATINDEX('%' + @searchLast + '%', lastname) as LLIndex,

CONVERT(BIT, PATINDEX('%' + @searchFirst + '%', firstname)) as HasFF,

CONVERT(BIT, PATINDEX('%' + @searchFirst + '%', lastname)) as HasFL, 

CONVERT(BIT, PATINDEX('%' + @searchLast + '%', firstname)) as HasLF,

CONVERT(BIT, PATINDEX('%' + @searchLast + '%', lastname)) as HasLL,

DIFFERENCE(firstname, @searchFirst) * DIFFERENCE(firstname, @searchFirst) as FFDiffSq, DIFFERENCE(lastname, @searchFirst) * DIFFERENCE(lastname, @searchFirst) as FLDiffSq, DIFFERENCE(firstname, @searchLast) * DIFFERENCE(firstname, @searchLast) as LFDiffSq, DIFFERENCE(lastname, @searchLast) * DIFFERENCE(lastname, @searchLast) as LLDiffSq,

DIFFERENCE(firstname, @searchFirst) * DIFFERENCE(firstname, @searchFirst) + DIFFERENCE(lastname, @searchFirst) * DIFFERENCE(lastname, @searchFirst) + DIFFERENCE(firstname, @searchLast) * DIFFERENCE(firstname, @searchLast) + Difference(lastname, @searchLast) * Difference(lastname, @searchLast) as SumDiffSquares,

DIFFERENCE(firstname, @searchFirst) * DIFFERENCE(firstname, @searchFirst) * 2 + DIFFERENCE(lastname, @searchFirst) * DIFFERENCE(lastname, @searchFirst) + DIFFERENCE(firstname, @searchLast) * DIFFERENCE(firstname, @searchLast) + DIFFERENCE(lastname, @searchLast) * DIFFERENCE(lastname, @searchLast) * 2
+ CONVERT(BIT, PATINDEX('%' + @searchFirst + '%', firstname)) * 4 + CONVERT(BIT, PATINDEX('%' + @searchFirst + '%', lastname)) + CONVERT(BIT, PATINDEX('%' + @searchLast + '%', firstname)) + CONVERT(BIT, PATINDEX('%' + @searchLast + '%', lastname)) * 4 as TotalRank

FROM Contacts

ORDER BY TotalRank Desc, HasLL Desc, HasFF Desc, HasFL Desc, HasLF Desc, LLIndex, FFIndex, FLIndex, LFIndex, LLDelta, FFDelta

如何根据where子句匹配实现排名（没有全文索引）

2 个答案: