Question

尝试编写SQL Server 2008 XML查询。我在这里简化了我的例子，但是给出了这些数据：

create table #parentinfo (name varchar(50), city varchar(50), state varchar(50))
insert #parentinfo values ('joe', 'yonkers', 'ny')
insert #parentinfo values ('sue', 'sacremento', 'ca')

-- parentname is foreign key to name field in #parentinfo
create table #childinfo (parentname varchar(50), childxml xml)
insert #childinfo values ('joe', '<child>mary</child><child>ben</child>')
insert #childinfo values ('sue', '<child>sally</child><child>roger</child>')

我需要输出如下所示的XML：

<parentinfo>
<parent>
    <name>joe</name>
    <city>yonkers</city>
    <state>ny</state>
    <children>
        <child>mary</child>
        <child>ben</child>
    </children>
</parent>
<parent>
    <name>sue</name>
    <city>sacremento</city>
    <state>ca</state>
    <children>
        <child>sally</child>
        <child>roger</child>
    </children>
</parent>
</parentinfo>

此查询执行此操作：

select  name,
    city,
    state, 
    (select childxml
    from #childinfo c
    where  c.parentname = p.name
    --for xml auto, type, elements
    ) as 'children'
from #parentinfo p
group by name, city, state
for xml path('parent')

但是，当其中一个父项在childinfo表中有一个额外的行时，我遇到了问题。将此行添加到表中：

insert #childinfo values ('joe', '<child>chucky</child><child>pebbles</child>')

我的查询爆炸说子查询返回的值超过1。我需要处理这种情况。有谁知道如何解决？

感谢。

Answer 1

如果您有一个“常规”子表 - 只有一个孩子的名字 - 而不是一个XML片段，您可以使用此查询来获得您正在寻找的内容：

create table #parentinfo (name varchar(50), city varchar(50), state varchar(50))
insert #parentinfo values ('joe', 'yonkers', 'ny')
insert #parentinfo values ('sue', 'sacremento', 'ca')

-- parentname is foreign key to name field in #parentinfo
create table #childinfo (parentname varchar(50), childname VARCHAR(50))
insert #childinfo values ('joe', 'mary')
insert #childinfo values ('joe', 'ben')
insert #childinfo values ('sue', 'sally')
insert #childinfo values ('sue', 'roger')

insert #childinfo values ('joe', 'chucky')
insert #childinfo values ('joe', 'pebbles')

select  name,
    city,
    state, 
    (select childname as 'child'
     from #childinfo c
     where c.parentname = p.name
     order by childname
     for xml PATH(''), type
    ) as 'children'
from #parentinfo p
group by name, city, state
for xml path('parent'), root('parentinfo')

结果输出为：

<parentinfo>
  <parent>
    <name>joe</name>
    <city>yonkers</city>
    <state>ny</state>
    <children>
      <child>ben</child>
      <child>chucky</child>
      <child>mary</child>
      <child>pebbles</child>
    </children>
  </parent>
  <parent>
    <name>sue</name>
    <city>sacremento</city>
    <state>ca</state>
    <children>
      <child>roger</child>
      <child>sally</child>
    </children>
  </parent>
</parentinfo>

Answer 2

select  name,
    city,
    state, 
    (select childxml as '*'
     from #childinfo c
     where  c.parentname = p.name
     for xml path(''), type
    ) as 'children'
from #parentinfo p
group by name, city, state
for xml path('parent')

结果：

<parent>
  <name>joe</name>
  <city>yonkers</city>
  <state>ny</state>
  <children>
    <child>mary</child>
    <child>ben</child>
    <child>chucky</child>
    <child>pebbles</child>
  </children>
</parent>
<parent>
  <name>sue</name>
  <city>sacremento</city>
  <state>ca</state>
  <children>
    <child>sally</child>
    <child>roger</child>
  </children>
</parent>

在SQL Server 2008中输出嵌套的XML

2 个答案: