Oracle 12 XMLElement:如果值_expr为空，则无标记

早上好，来自德国

现在，如果值_expr为null，是否有方法抑制XMLElement中的整个标记

类似：抑制宾果标记：

SELECT XMLELEMENT( "artno", trim(artno) )
     , XMLELEMENT( "bingo", NULL )
  FROM articlemasterdata
 WHERE artno = '770100C'

<artnr>770100C</artnr>
<bingo></bingo>

即使XMLTYPE也会提供一个空标记：

SELECT XMLTYPE( XMLELEMENT( "artno", trim(artno) ).getclobval() ) 
    ,  XMLTYPE( XMLELEMENT( "bingo", null ).getclobval() )
  FROM articlemasterdata 
 WHERE artno = '770100C';

<artnr>770100C</artnr>
<bingo></bingo>

谢谢,

Joachim

您可以使用xmlforest而不是xmlelement：

或者更现实一点：

-- CTE for dummy table
with articlemasterdata (artno, bingo) as (
  select '770100A', 'legs eleven' from dual
  union all
  select '770100C', null from dual
)
-- actual query
SELECT XMLELEMENT( "artno", trim(artno) )
     , XMLFOREST( bingo as "bingo")
  FROM articlemasterdata
 WHERE artno = '770100A'
    OR artno = '770100C';

XMLELEMENT("ARTNO",TRIM(ARTNO))                                                  XMLFOREST(BINGOAS"BINGO")                                                       
-------------------------------------------------------------------------------- --------------------------------------------------------------------------------
<artno>770100A</artno>                                                           <bingo>legs eleven</bingo>                                                      
<artno>770100C</artno>                                                                                                                                           

甚至：

SELECT XMLELEMENT( "root",
         XMLELEMENT( "artno", trim(artno) )
       , XMLFOREST( bingo as "bingo")
       )
  FROM articlemasterdata
 WHERE artno = '770100A'
    OR artno = '770100C';

XMLELEMENT("ROOT",XMLELEMENT("ARTNO",TRIM(ARTNO)),XMLFOREST(BINGOAS"BINGO"))    
--------------------------------------------------------------------------------
<root><artno>770100A</artno><bingo>legs eleven</bingo></root>
<root><artno>770100C</artno></root>

您可以使用xmlforest而不是xmlelement：

或者更现实一点：

-- CTE for dummy table
with articlemasterdata (artno, bingo) as (
  select '770100A', 'legs eleven' from dual
  union all
  select '770100C', null from dual
)
-- actual query
SELECT XMLELEMENT( "artno", trim(artno) )
     , XMLFOREST( bingo as "bingo")
  FROM articlemasterdata
 WHERE artno = '770100A'
    OR artno = '770100C';

XMLELEMENT("ARTNO",TRIM(ARTNO))                                                  XMLFOREST(BINGOAS"BINGO")                                                       
-------------------------------------------------------------------------------- --------------------------------------------------------------------------------
<artno>770100A</artno>                                                           <bingo>legs eleven</bingo>                                                      
<artno>770100C</artno>                                                                                                                                           

甚至：

SELECT XMLELEMENT( "root",
         XMLELEMENT( "artno", trim(artno) )
       , XMLFOREST( bingo as "bingo")
       )
  FROM articlemasterdata
 WHERE artno = '770100A'
    OR artno = '770100C';

XMLELEMENT("ROOT",XMLELEMENT("ARTNO",TRIM(ARTNO)),XMLFOREST(BINGOAS"BINGO"))    
--------------------------------------------------------------------------------
<root><artno>770100A</artno><bingo>legs eleven</bingo></root>
<root><artno>770100C</artno></root>