Joining multiple queries in Data template XML Publisher

Joining multiple queries in XML Publisher can be done by 2 methods

1) Query Link for below dataQuery

 <link name="LINK1" parentQuery="Q1" parentColumn="VALUE1" childQuery="Q2" childColumn="COLUMN1"/>  
 <link name="LINK2" parentQuery="Q2" parentColumn="COLUMN1" childQuery="Q3" childColumn="COLUMN6"/>  

2) Column link between multiple queries
 Multiple queries can be linked in XML Data Template by passing the column from parent query as parameter to the child sqlStatement. This approach is recommended over using Query link and there is no limit for number of queries to be linked.

 <dataQuery>  
   <sqlStatement name="Q1">  
   <![CDATA[  
           SELECT XT1.VALUE1 from   
                XX_TABLE1 XT1  
                WHERE 1=1  
                     AND XT1.COLUMN1 = :PARAMETER1 <your parameter is optionalter>  
   ]]>  
   </sqlStatement>  
   <sqlStatement name="Q2">  
   <![CDATA[  
           SELECT XT2.COLUMN1, XT2.COLUMN2 from   
                XX_TABLE2 XT2  
                WHERE 1=1  
                     AND XT2.COLUMN1 = :VALUE1  
   ]]>  
   </sqlStatement>       
   <sqlStatement name="Q3">  
   <![CDATA[  
           SELECT XT3.COLUMN5, XT3.COLUMN6 from   
                XX_TABLE3 XT3  
                WHERE 1=1  
                     AND XT3.COLUMN6 = :COLUMN1  
   ]]>  
   </sqlStatement>  
 </dataQuery>       

The same can be represented in datastructure of XML Data template.

 <dataStructure>  
   <group name="G_PARENT"  source="Q1">  
           <element name="VALUE1"                value="VALUE1"/>       
           <group name="G_HDR_DETAILS"  source="Q2">  
                <element name="COLUMN1"                value="COLUMN1"/>  
                <element name="COLUMN2"                value="COLUMN2"/>  
                          <group name="G_LINE_DETAILS"  source="Q3">  
                               <element name="COLUMN5"        value="COLUMN5"/>  
                               <element name="COLUMN6"        value="COLUMN6"/>       
                          </group>                 
           </group>  
      </group>  
 </dataStructure>