ALTER TABLE rop_contenus
CHANGE `publication_debut` `publication_debut` DATE NULL DEFAULT NULL ,CHANGE `publication_fin` `publication_fin` DATE NULL DEFAULT NULL ;
UPDATE rop_contenus
SET `publication_debut` = NULL
WHERE `publication_debut` < "1000-01-01"
UPDATE rop_contenus
SET `publication_fin` = NULL
WHERE `publication_fin` < "1000-01-01"