Question

假设我将员工数据存储在我的日志表的xml列中。有时，数据也会在存储过程的xml列中更新。

以下是示例示例

DECLARE @XML1 XML
DECLARE @XML2 XML

SET @XML1 = 
'<NewDataSet> 
<Employee>
<EmpID>1005</EmpID>
<Name> keith </Name>
<DOB>12/02/1981</DOB>
<DeptID>ACC001</DeptID>
<Salary>10,500</Salary>
</Employee>
</NewDataSet>'

SET @XML2 = 
'<NewDataSet> 
<Employee>
<EmpID>1006</EmpID>
<Name> keith </Name>
<DOB>05/02/1981</DOB>
<DeptID>ACC002</DeptID>
<Salary>10,900</Salary>
</Employee>
</NewDataSet>'

我需要显示的两个xml数据存在一些差异，如旧值＆amp;新值作为sql的输出

Old Value             New Value
---------             ---------
1005                  1006
12/02/1981            05/02/1981
ACC001                ACC002
10,500                10,900

我只需要像上面那样展示差异。因此，请指导我如何使用XQuery比较两个xml数据，并仅在SQL Server中以上述方式显示差异。请引导我使用代码段。感谢

Answer 1

;with XML1 as
(
  select T.N.value('local-name(.)', 'nvarchar(100)') as NodeName,
         T.N.value('.', 'nvarchar(100)') as Value
  from @XML1.nodes('/NewDataSet/Employee/*') as T(N)
),
XML2 as
(
  select T.N.value('local-name(.)', 'nvarchar(100)') as NodeName,
         T.N.value('.', 'nvarchar(100)') as Value
  from @XML2.nodes('/NewDataSet/Employee/*') as T(N)
)
select coalesce(XML1.NodeName, XML2.NodeName) as NodeName, 
       XML1.Value as Value1, 
       XML2.Value as Value2
from XML1
  full outer join XML2
    on XML1.NodeName = XML2.NodeName
where coalesce(XML1.Value, '') <> coalesce(XML2.Value, '')

结果：

NodeName             Value1               Value2
-------------------- -------------------- --------------------
EmpID                1005                 1006
DOB                  12/02/1981           05/02/1981
DeptID               ACC001               ACC002
Salary               10,500               10,900

Answer 2

我没有您想要的完全输出 - 但至少您可以很好地比较旧值和新值：

;WITH OldData AS
(
SELECT 
    @XML1.value('(/NewDataSet/Employee/EmpID)[1]', 'int') AS 'EmpID',
    @XML1.value('(/NewDataSet/Employee/Name)[1]', 'varchar(50)') AS 'Name',
    @XML1.value('(/NewDataSet/Employee/DOB)[1]', 'datetime') AS 'DOB',
    @XML1.value('(/NewDataSet/Employee/DeptID)[1]', 'varchar(50)') AS 'DeptID',
    @XML1.value('(/NewDataSet/Employee/Salary)[1]', 'varchar(25)') AS 'Salary'
),
NewData AS
(
SELECT 
    @XML2.value('(/NewDataSet/Employee/EmpID)[1]', 'int') AS 'EmpID',
    @XML2.value('(/NewDataSet/Employee/Name)[1]', 'varchar(50)') AS 'Name',
    @XML2.value('(/NewDataSet/Employee/DOB)[1]', 'datetime') AS 'DOB',
    @XML2.value('(/NewDataSet/Employee/DeptID)[1]', 'varchar(50)') AS 'DeptID',
    @XML2.value('(/NewDataSet/Employee/Salary)[1]', 'varchar(25)') AS 'Salary'
)
SELECT
    'Old values', od.*
FROM OldData od
UNION
SELECT 'New values', nd.*
FROM NewData nd

为您提供输出：

            EmpID  Name   DOB                       DeptID   Salary
Old values  1005   keith  1981-12-02 00:00:00.000   ACC001   10,500
New values  1006   keith  1981-05-02 00:00:00.000   ACC002   10,900

SQL Server非常适合存储和操作数据 - 但这样的表示应该在前端应用程序（如ASP.NET应用程序）中完成 - 而不是在T-SQL中...

Answer 3

我来不及!!!但是我发现，如果上面显示的员工XML有多条记录，那么带有CTE的JOIN查询会返回不正确的结果。

我有以下XML输入

DECLARE @XML1 XML
DECLARE @XML2 XML

SET @XML1 = 
'<NewDataSet> 
<Employees>
    <Employee>
        <Name> keith </Name>
        <EmpID> 1005 </EmpID>
        <DOB>12/02/1981</DOB>
        <DeptID>ACC001</DeptID>
        <Salary>10,500</Salary>
    </Employee>
    <Employee>
        <Name> keith </Name>
        <EmpID> 1004 </EmpID>
        <DOB>12/02/1981</DOB>
        <DeptID>ACC001</DeptID>
        <Salary>10,500</Salary>
    </Employee>
</Employees>
</NewDataSet>'

    SET @XML2 = 
    '<NewDataSet> 
    <Employees>
        <Employee>
            <Name> keith </Name>
            <EmpID> 1005 </EmpID>
            <DOB>12/02/1981</DOB>
            <DeptID>ACC001</DeptID>
            <Salary>10,500</Salary>
        </Employee>
        <Employee>
            <Name> keith </Name>
            <EmpID> 1004 </EmpID>
            <DOB>12/02/1981</DOB>
            <DeptID>ACC001</DeptID>
            <Salary>10,501</Salary>
        </Employee>
        <Employee>
            <Name> keith1 </Name>
            <EmpID> 10040 </EmpID>
            <DOB>12/02/1981</DOB>
            <DeptID>ACC001</DeptID>
            <Salary>10,501</Salary>
        </Employee>
    </Employees>
    </NewDataSet>'

我将使用以下查询来查找差异

select  T.N.value('local-name(.)', 'nvarchar(100)') as NodeName,
T.N.value('.', 'nvarchar(100)') as Value
from @XML2.nodes('/NewDataSet/Employees/Employee/*') as T(N)

EXCEPT

select  T.N.value('local-name(.)', 'nvarchar(100)') as NodeName,
T.N.value('.', 'nvarchar(100)') as Value
from @XML1.nodes('/NewDataSet/Employees/Employee/*') as T(N)

希望这有帮助!!!

在SQL Server中使用XQuery比较两组XML数据

3 个答案: