SQL & PL/SQL

Hi,

Under Oracle 19.c I try to make a select that transform a column into an hypertext link. But I get an error message ;

I try to change the SQL request but i get an error :

select ID,
      NOM,
      "PRÉNOM",
      TITRE,
      CASE LIEN_CV
      WHEN NULL THEN NULL
      ELSE '<a href="' || LIEN_CV ||'">CV</a>' as "LIEN"
      END
 from EC_CV 

ORA-20999: Echec de l'analyse de la requête SQL. ORA-06550 : ligne 7, colonne 44: ORA-00905: mot-clé absent

If i change to asimpler select there is no error;

select ID,
      NOM,
      "PRÉNOM",
      TITRE,
      CASE LIEN_CV
      WHEN NULL THEN NULL
      ELSE 'test'
      END
 from EC_CV 

The DDL of the table :

CREATE TABLE "EC_CV" 
  (    "ID" NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY MINVALUE 1 MAXVALUE 9999999999999999999999999999 INCREMENT BY 1 START WITH 1 CACHE 20 NOORDER  NOCYCLE  NOKEEP  NOSCALE  NOT NULL ENABLE, 
    "NOM" VARCHAR2(50), 
    "PRÉNOM" VARCHAR2(50), 
    "TITRE" VARCHAR2(255), 
    "RGPD" VARCHAR2(50), 
    "LIEN_CV" VARCHAR2(255), 
    "LIEN_PROFIL" VARCHAR2(255), 
     PRIMARY KEY ("ID")
 USING INDEX  ENABLE
  ) ;

Best regards.