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Transform XML Output Of SQL Query To HTML Using "For XML" AUTO Statement With XSLT In C#

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This article describes how to transform the XML output of SQL query statements using FOR XML AUTO to HTML using XSLT.

Normally, we execute the query using ExecuteNonQuery statement and fill the output into a data table. We can access the data in the data table by giving column name and row number in the looping method. This makes us work on extra coding and takes a lot of time to get the correct data from executed query. So, I moved to XML because, in XML, we can fetch the values easily and quickly without writing too much code.     

FOR XML Clause in SQL

Basically, we have four types of FOR XML clause in SQL.

  • FOR XML RAW
  • FOR XML AUTO
  • FOR XML EXPLICIT
  • FOR XML PATH

Each of the above types satisfies its own need. When you want full control over the produced XML, you use FOR XML EXPLICIT, but it is difficult to understand, read, or maintain. FOR XML AUTO produces the most readable SELECT statement. The RAW option is rarely used and therefore not discussed. The PATH option allows you to mix attributes and elements easier. Here, I gona use FOR XML AUTO.

Table Name - Contact_Details

Contact_IDContact_NumberContact_NameContact_Location
001088888888MohanChennnai
002099999999AbilashBangalore


If we want the output as in XML format, we need to add the FOR XML AUTO statement.

 

  1. SELECT * FROM Contact_Details FOR XML AUTO  

This query gives the output like,

  1. < Contact_Details Contact_ID=’001’ Contact_Number=’ 088888888’ Contact_Name=’Mohan’ Contact_Location=’Chennai’/>  
  2. < Contact_Details Contact_ID=’002’ Contact_Number=’ 099999999’ Contact_Name=’Abilash’ Contact_Location=’Bangalore’/>  

The XML which we got in output is not in user-friendly format. We need each field as an attribute so, that we can access the values using XPATH. To achieve that, we need to add the ELEMENTS parameter with the query.

 

  1. SELECT * FROM Contact_Details FOR XML AUTO, ELEMENTS  

This query gives the output like,

  1. < Contact_Details>  
  2.     <Contact_ID>001</Contact_ID>  
  3.     <Contact_Number>088888888</Contact_Number>  
  4.     <Contact_Name>Mohan</Contact_Name>  
  5.     <Contact_Location>Chennai</Contact_Location>  
  6. </ Contact_Details>  
  7. < Contact_Details>  
  8.     <Contact_ID>002</Contact_ID>  
  9.     <Contact_Number>099999999</Contact_Number>  
  10.     <Contact_Name>Abilash</Contact_Name>  
  11.     <Contact_Location>Bangalore</Contact_Location>  
  12. </ Contact_Details>  

So, this is the exact XML format we need.

Now, we are going to create XML DOCUMENT and write this output XML into that XML document in coding. To read the query in XML format, we need to execute the query using ExecuteXmlReader() function. 

  1. XmlReader XMLReader = new XmlReader();  
  2. XmlDocument XmlDoc = new XmlDocument();  
  3. SqlCommand Cmd = new SqlCommand(Query, Conn);  
  4. XMLReader = cmd.ExecuteXmlReader();  
  5. XPathDocument xPathDoc = new XPathDocument(XMLReader);  
  6. XPathNavigator xPathNavi = xPathDoc.CreateNavigator();  
  7. XmlDoc.LoadXml(XpathNavi.OuterXml);  

Now, we got the full structured XML Document. Using this, we will transform the data into HTML format using XSLT.

Before transforming, we need to create one XSLT file to assign the values from XMLDocument to HTML format.

Contact_Details.xslt

  1. <?xml version=”1.0” encoding=”utf-8”?>  
  2. <xsl:stylesheet version=”1.0” xmlns:xsl=”http://www.w3.org/1999/XSL/Tranform”>  
  3.     <xsl:output method=”xml” indent=”yes” omit-xml-declaration=”yes”>  
  4.         <xsl:template match=”/*”>  
  5.             <table>  
  6.                 <tr>// Column heading  
  7.                     <td>ContactID</td>  
  8.                     <td>ContactNumber</td>  
  9.                     <td>ContName</td>  
  10.                     <td>ContactLocation</td>  
  11.                 </tr>  
  12.                 <xsl:for-each select=”/ Contact_Details”>  
  13.                     <tr>// inserting XML data into HTML table  
  14.                         <td>  
  15.                             <xsl:value-of select=”/Contact_details/Contact_ID” </td> // using XPath we can access the value from XML Document  
  16.                                 <td>  
  17.                                     <xsl:value-of select=”/Contact_details/Contact_Number” </td>  
  18.                                 <td>  
  19.                               <xsl:value-of select=”/Contact_details/Contact_Name” </td>  
  20.                           <td>  
  21.                        <xsl:value-of select=”/Contact_details/Contact_Location” </td>  
  22.                     </tr>  
  23.                 </xsl:for-each>  
  24.             </table>  
  25.         </xsl:template>  
  26. </xsl:stylesheet>  

Now, we have XML Document and XSLT file. In the next step, we are going to transform the XML Document into HTML using XSLT. To do this, we pass the XMLDocument and XSLT file to separate functions and get fully formed HTML strings in return.

  1. Public static string TransformXMLTOHTML(XmlDocument XMLDoc, String XSLTFilename) {  
  2.     StringWriter HTMLString = new StringWriter();  
  3.     XslCompiledTransform Xmltransform = new XslCompiledTransform();  
  4.     XmlTransform.Load(XSLTFilename); // Load XSLT File  
  5.     Xmltranform.Transform(XMLDoc, null, Result); // transform XML into HTML  
  6.     Return HTMLString.ToString();  
  7. }  
posted Jan 10 by Shivaranjini

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Related Articles

In this article, I'm going to use XML RAW type to get XML format output from the data of two tables. Here, a question may rise, why can’t we do that by XML AUTO type. Yes, we can. But when we using XML AUTO, the output XML will consist too many XML nodes and there is no order in the XML nodes when we use JOIN statement in the query when we use two tables in single query. You can understand this in the following explanation.

Table: Student_Details

Student_IDContact_NumberStudent_NameStudent_Location
001088888888MohanChennai
002099999999AbilashBangalore


Table: Student_Marks 
 

Student_IDExam_TypeScored_MarkScored_Percentage
001AnnualExam110086
002AnnualExam105080

So, these are my tables. The first table has the basic information about students while the second table has the marks details.

Here, our task is to get the information about the students and attach the marks details with each student, based on the StudentID because here, StudentID is the primary key for both tables. This can be done in different ways. I am going to do that using XML Raw elements.

Let’s write the query to select the values using XML AUTO elements.

 

  1. SELECT Student_ID,Contact_Number,Student_Name,Student_Location,MarkDetails.Exam_Type AS ExamType,MarkDetails.Scored_Mark AS Marks,MarkDetails.Scored_Percentage AS Percentage FROM Student_Details LEFT JOIN Student_Marks AS MarkDetails ON MarkDetails.Student_ID=Student_ID for XML AUTO,ELEMENT  

This query will give output like the following.

  1. < Student_Details>  
  2.     < Student_ID>001  
  3.         < /Student_ID>  
  4.             < Contact_Number>088888888  
  5.                 < /Contact_Number>  
  6.                     < Student_Name>Mohan  
  7.                         < /Student_Name>  
  8.                             < Student_Location>Chennai  
  9.                                 < /Student_Location>  
  10.                                     < ExamType>  
  11.                                         < ExamType>AnnualExam</ ExamType>  
  12.                                         < Marks>  
  13.                                             < Marks>1100</ Marks>  
  14.                                             < Percentage>  
  15.                                                 < Percentage>86</ Percentage>  
  16.                                             </ Percentage>  
  17.                                         </ Marks>  
  18.                                     </ ExamType>  
  19.                                 </ Student_Details>  
  20.                                 < Student_Details>  
  21.                                     < Student_ID>002  
  22.                                         < /Student_ID>  
  23.                                             < Contact_Number>099999999  
  24.                                                 < /Contact_Number>  
  25.                                                < Student_Name>Abilash  
  26.                                               < /Student_Name>  
  27.                                            < Student_Location>Bangalore  
  28.                                          < /Student_Location>  
  29.                                       < ExamType>  
  30.                                     < ExamType>AnnualExam</ ExamType>  
  31.                                   < Marks>  
  32.                                < Marks>1050</ Marks>  
  33.                             < Percentage>  
  34.                          < Percentage>80</ Percentage>  
  35.                      </ Percentage>  
  36.                </ Marks>  
  37.        </ ExamType>  
  38.  </ Student_Details>  

The output XML format is not what we have expected. To overcome this, we are moving to XML RAW type method to get the well designed XML with root node.

Let's try the same query with XML RAW Type.

 

  1. SELECT Student_ID,Contact_Number,Student_Name,Student_Location,MarkDetails.Exam_Type AS ExamType,MarkDetails.Scored_Mark AS Marks,MarkDetails.Scored_Percentage AS Percentage FROM Student_Details LEFT JOIN Student_Marks AS MarkDetails ON MarkDetails.Student_ID=Student_ID for XML RAW(‘Student’),ELEMENTS,TYPE  

This query will produce the output like following.

  1. < Student>  
  2.       < Student_ID>001< /Student_ID>  
  3.          < Contact_Number>088888888< /Contact_Number>  
  4.             < Student_Name>Mohan< /Student_Name>  
  5.                < Student_Location>Chennai< /Student_Location>  
  6.                   < ExamType>AnnualExam</ ExamType>  
  7.                      < Marks>1100</ Marks>  
  8.                      Percentage>86</ Percentage>  
  9.                   </ Student>  
  10.                   < Student>  
  11.                < Student_ID>002< /Student_ID>  
  12.             < Contact_Number>099999999< /Contact_Number>  
  13.          < Student_Name>Abilash< /Student_Name>  
  14.       < Student_Location>Bangalore< /Student_Location>  
  15.       < ExamType>AnnualExam</ ExamType>  
  16.       Marks>1050</ Marks>  
  17.      < Percentage>80</ Percentage>  
  18. </ Student>  

The output XML which we got now is well-formatted XML Document and in more user understandable form.

By using this, we can do more process in coding. Please refer my previous article where I have given how to transform the constructed XML into HTML document using XSLT.

I hope this article is useful.

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