XML Data Type Methods(一)

XML Data Type Methods(一)
/*XML Data Type Methods:
1.The query('XQuery') method retrieves(vt.检索,重新得到) a subset of untyped XML from the target XML instance

2.The value('XQuery',dataType) method returns a scalar value(标量值) from the targeted XML document.
    The returned value is converted to the data type you specify when you call the method.

3.The exist('XQuery') method lets you test for the existence of an element or one of its values

4.The nodes('XQuery') method returns what is essentially a table that includes one column.
    That means you should use the method only in those parts of a statement that can handle rowset views, such as the FROM clause.
    It also means that, when you call the nodes() method, you must assign a table alias and column alias to the rowset view returned by the method
5.The modify('XQuery') method lets you update that data
*/

DECLARE @StoresTable  TABLE
(
  StoreID INT IDENTITY(1,1) PRIMARY KEY,
  Survey_untyped XML,
  Survey_typed XML
)

 INSERT INTO @StoresTable(Survey_untyped,Survey_typed)
 VALUES
 (
  '<UnifiedRequest>
  <CommonInfo>
    <Version>1.14</Version>
    <Username>EC</Username>
  </CommonInfo>
  <OrderInfo>
    <CompanyCode>1003</CompanyCode>
    <PayTermsCode>024</PayTermsCode>
  </OrderInfo>
</UnifiedRequest>',
'<UnifiedRequest
   xmlns:i="http://www.w3.org/2001/XMLSchema-instance"
   xmlns="http://tempuri.org/UnifiedRequest.xsd">
  <CommonInfo>
    <Version>1.14</Version>
    <Username>EC</Username>
  </CommonInfo>
  <OrderInfo>
    <CompanyCode>1003</CompanyCode>
    <PayTermsCode>024</PayTermsCode>
  </OrderInfo>
</UnifiedRequest>'
)

--1.UntypedColumn
--1.1 query(xpathParameter) method
SELECT
  Survey_untyped.query('/UnifiedRequest/OrderInfo') AS Info_typed
FROM
  @StoresTable
/*Result:
<OrderInfo>
  <CompanyCode>1003</CompanyCode>
  <PayTermsCode>024</PayTermsCode>
</OrderInfo>
*/
--1.2 value(xpathParameter) method
SELECT
  Survey_untyped.value('(/UnifiedRequest/OrderInfo/CompanyCode/text())[1]','INT') AS CompanyCode
FROM
  @StoresTable

--1.3 exist(xpathParameter) method
SELECT TOP(1)
  CASE
    WHEN Survey_untyped.exist('/UnifiedRequest/OrderInfo/CompanyCode/text()')=1 THEN 'Found'
    ELSE 'Not Found'
  END
FROM
  @StoresTable

--1.4 nodes(xpathParameter) method
DECLARE @bikes XML
SET @bikes =
  '<Products>
    <Product>Mountain</Product>
    <Product>Road</Product>
   </Products>'
SELECT
  Category.query('./text()') AS BikeTypes1,--return a subset of xml
  Category.value('(./text())[1]','VARCHAR(20)') AS BikeTypes2--return string
FROM
  @bikes.nodes('/Products/Product')
    AS Bike(Category);
/*Result
    BikeTypes1 BikeTypes2
    ---------------------------
    Mountain    Mountain
    Road        Road
*/

--2.TypedColumn which contains namespace
--2.1 query(xpathParameter) method
;WITH XMLNAMESPACES(DEFAULT 'http://tempuri.org/UnifiedRequest.xsd')
SELECT
  Survey_typed.query('/UnifiedRequest/OrderInfo') AS Info_typed
FROM
  @StoresTable
/*Result:
<p1:OrderInfo xmlns:p1="http://tempuri.org/UnifiedRequest.xsd">
  <p1:CompanyCode>1003</p1:CompanyCode>
  <p1:PayTermsCode>024</p1:PayTermsCode>
</p1:OrderInfo>
*/

;WITH XMLNAMESPACES('http://tempuri.org/UnifiedRequest.xsd' AS UFD)
SELECT
  Survey_typed.query('/UFD:UnifiedRequest/UFD:OrderInfo') AS Info_typed
FROM
  @StoresTable
/*Result:
<UFD:OrderInfo xmlns:UFD="http://tempuri.org/UnifiedRequest.xsd">
  <UFD:CompanyCode>1003</UFD:CompanyCode>
  <UFD:PayTermsCode>024</UFD:PayTermsCode>
</UFD:OrderInfo>
*/

SELECT
  Survey_typed.query('declare namespace UFR="http://tempuri.org/UnifiedRequest.xsd";
    /UFR:UnifiedRequest/UFR:OrderInfo') AS Info_typed
FROM
  @StoresTable;
/*Result:
<UFR:OrderInfo xmlns:UFR="http://tempuri.org/UnifiedRequest.xsd">
  <UFR:CompanyCode>1003</UFR:CompanyCode>
  <UFR:PayTermsCode>024</UFR:PayTermsCode>
</UFR:OrderInfo>
*/

;WITH XMLNAMESPACES('http://tempuri.org/UnifiedRequest.xsd' AS UFD)
SELECT
  Survey_typed.query('/UFD:UnifiedRequest') AS Info_typed
FROM
  @StoresTable;
/*Result:
<UnifiedRequest xmlns="http://tempuri.org/UnifiedRequest.xsd" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
  <CommonInfo>
    <Version>1.14</Version>
    <Username>EC</Username>
  </CommonInfo>
  <OrderInfo>
    <CompanyCode>1003</CompanyCode>
    <PayTermsCode>024</PayTermsCode>
  </OrderInfo>
</UnifiedRequest>
*/

--2.2 value(xpathParameter,dataType) method
;WITH XMLNAMESPACES(DEFAULT 'http://tempuri.org/UnifiedRequest.xsd')
SELECT
  --Result:1003
  Survey_typed.value('(/UnifiedRequest/OrderInfo/CompanyCode/text())[1]','INT') AS CompanyCode
FROM
  @StoresTable

SELECT
  --Result:1003
  Survey_typed.value('declare namespace UFD="http://tempuri.org/UnifiedRequest.xsd";
(/UFD:UnifiedRequest/UFD:OrderInfo/UFD:CompanyCode/text())[1]','INT') AS CompanyCode
FROM
  @StoresTable

--2.3 exist(xpathParameter) method
;WITH XMLNAMESPACES(DEFAULT 'http://tempuri.org/UnifiedRequest.xsd')
SELECT TOP(1)
  CASE
    WHEN Survey_typed.exist('/UnifiedRequest/OrderInfo/CompanyCode/text()')=1 THEN 'Found'
    ELSE 'Not Found'
  END

FROM
  @StoresTable

--2.4 nodes(xpathParameter) method
DECLARE @bikes2 XML
SET @bikes2 =
  '<Products xmlns="http://tempuri.org/UnifiedRequest.xsd">
    <Product>Mountain</Product>
    <Product>Road</Product>
   </Products>'

;WITH XMLNAMESPACES(DEFAULT 'http://tempuri.org/UnifiedRequest.xsd')
SELECT
  Category.query('./text()') AS BikeTypes1,--return a subset of xml
  Category.value('(./text())[1]','VARCHAR(20)') AS BikeTypes2--return string
FROM
  @bikes2.nodes('/Products/Product') AS Bike(Category);
/*Result
    BikeTypes1 BikeTypes2
    ---------------------------
    Mountain    Mountain
    Road        Road
*/