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我有一种情况，我试图从临时表中获取未填充字段的列表到逗号分隔的语句中。

因此，给定示例数据（它将始终是单行，并且可能在临时表中（因为实际数据将来自多个源表））：

Field1     Field2   Field3   Field4
'aaa'      null      ''      null

和的映射表

FieldName    Question   Section
'Field1'     'Q1'       'Sec1'
'Field2'     'Q2'       'Sec1'
'Field3'     'Q3'       'Sec2'
'Field4'     'Q4'       'Sec2'

我想要以下结果：

Section   UnansweredQs
'Sec1'    'Q2'
'Sec2'    'Q3, Q4'

我已经通过以下方式获得了逗号分隔的问题列表：

create table #testData (f1 varchar(50), f2 int, f3 varchar(50), f4 varchar(50))
create table #qlist (fieldName varchar(5), question varchar(3), section varchar(5))

insert into #qlist values ('f1', 'q1', 'sec1'), ('f2', 'q2', 'sec1'), ('f3', 'q3', 'sec2'), ('f4', 'q4', 'sec2')

insert into #testData values ('asda', null, '', null)

然后

declare @usql nvarchar(max) = ''
declare @sql nvarchar(max)
declare @xml xml

--build a gargantuan set of union statements, comparing the column value to null/'' and putting q# if it is
set @usql = 
    (
    select 'select case when ' + c.name + ' is null or ' + c.Name + ' = '''' then ''' + q.question + ', '' else '''' end from #testData union '
    from tempdb..syscolumns c
    inner join #qlist q
        on c.name = q.fieldName
    where c.id = object_id('tempdb..#testData') 
    for xml path('')
    );
--remove the last 'union', append for xml path to pivot the rows into a single column of concatenated rows
set @usql = left(@usql, len(@usql) - 6) + ' for xml path('''')'

print @usql

--remove final comma
--get the position of the last comma in the select statment (ie after the final unanswered question)
declare @lastComma int = charindex(',', reverse(@usql))
--add the bit before the last comma, and the bit after the last comma but skip the actual comma :)
set @usql = left(@usql, len(@usql) - @lastComma) + right(@usql, @lastComma - 2)

exec (@usql)

有了这个我得到

XML_F52E2B61-18A1-11d1-B105-00805F49916B
----------------------------------------
q2, q3, q4

但是我无法将该结果集放入另一个表或变量中（通过insert into #tmpresult exec (@usql)方法）。

通常带有Msg 1086, Level 15, State 1, Line 1 The FOR XML clause is invalid in views, inline functions, derived tables, and subqueries when they contain a set operator. To work around, wrap the SELECT containing a set operator using derived table syntax and apply FOR XML on top of it.错误。

我尝试了各种方法，包装、移除工会、CTE，但无法让它发挥作用。

4

2 回答 2

1

无需使用动态 SQL 来执行此操作。

declare @X xml

set @X = (
         select *
         from #testData
         for xml path('root'), elements xsinil, type 
         )

select section,
       (
       select ', '+Q2.question
       from #qlist as Q2
       where Q1.section = Q2.section and
             @X.exist('/root/*[local-name() = sql:column("Q2.fieldName")][. = ""]') = 1
       for xml path(''), type
       ).value('substring(text()[1], 2)', 'varchar(max)') as UnansweredQs
from #qlist as Q1
group by Q1.section

SQL小提琴

于 2013-08-18T19:00:42.620 回答
1

我有一个问题要问你：

with cte as (
    select
        N.Name
    from Table1
        cross apply (values
           ('Field1', Field1),
           ('Field2', Field2),
           ('Field3', Field3),
           ('Field4', Field4)
        ) as N(Name,Value)
    where N.Value is null or N.Value = ''
)
select distinct
    T2.Section,
    stuff(
        (
            select ', ' + TT.Question
            from Table2 as TT
                inner join cte as c on c.Name = TT.FieldName
            where TT.Section = T2.Section
            for xml path(''), type
        ).value('.', 'nvarchar(max)')
    , 1, 2, '') as UnansweredQs
from Table2 as T2

你可以自己把它变成动态的:)

sql 小提琴演示

于 2013-08-16T12:50:14.780 回答