title: add columns in a CDS view and fill it with a condition
body: <p>I have been trying for several days, in a cds view, to convert a row of the acdoca table (here the amount of a debit/credit transaction, the hsl attribute in acdoca), into two columns debit and credit.</p>
  <p>The amount of a transaction would go into a column depending on the type of debit/credit (attribute drcrk in acdoca which returns H for a debit or S for a credit). Is there a solution to my problem or a doc accessible to a beginner to solve this problem
  (PS I don't know ABAP so if you have a solution using it is it possible to describe where and how to integrate it to Eclipse).</p>
  <p>I tried to declare a direct attribute in the view, to alter the view, but all this does not work. I have been told about the possibility of using a functional table, which seems to work, but I can't structure it correctly just in the typing of my tables.</p>
  <p>I can pass my view if necessary.</p>
  <pre><code> define view Z_test_dc as select from acdoca 
  inner join  bseg on acdoca.rbukrs = bseg.bukrs 
                  and bseg.belnr    = acdoca.belnr 
                  and bseg.gjahr    = acdoca.gjahr 
                  and bseg.buzei    = acdoca.buzei
  left outer join but000 on but000.partner = acdoca.kunnr
  left outer join t003t   on t003t.blart   = acdoca.blart
  {
      key acdoca.rbukrs,       //Société
      key acdoca.gjahr,        //Exercice comptable
      key acdoca.belnr,        //Numéro de pièce comptable
      key acdoca.racct,        //Numéro de compte    
      key acdoca.docln,        //Ligne d'écriture à six caractères pour ledger
          acdoca.kunnr,        //Client        
          acdoca.fiscyearper,  //Période/exercice
          acdoca.augbl,        //Nº pièce rapprochement
          acdoca.bldat,        //Date de la pièce
          acdoca.budat,        //Date comptable du document
          acdoca.blart,        //Type de pièce
          t003t.ltext,         //Description type de pièce
          acdoca.hsl,          //Montant en devise société
          acdoca.rhcur,        //Devise société
          acdoca.netdt,        //Date echéance nette
          bseg.madat,          //Data de la dernière relance
          bseg.mansp,          //Blocage relance
          bseg.manst,          //Niveau de relance   
          bseg.zterm,          //Conditions de paiement
          but000.bu_group,     //le regroupement du client
          bseg.valut,          //Date valeur delais
          bseg.sgtxt,          //Texte descriptif postes
          acdoca.drcrk         //type debit/credit (return H ou S)        
  }
  ... 
  </code></pre>