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SELECT DISTINCT b.persona_codigo, 
IFNULL(b.persona_numero_documento,'Otro'),
b.persona_nombres,
b.persona_apellido_paterno,
IFNULL(b.persona_apellido_materno,''),
IFNULL(c.perfil_nombre,'CONFERENCISTA'),
IFNULL(d.grado_academico_nombre,'')
FROM persona b
LEFT OUTER JOIN usuario a on b.persona_codigo = a.persona_codigo
LEFT OUTER JOIN perfil c on a.perfil_codigo = c.perfil_codigo
LEFT OUTER JOIN grado_academico d on b.grado_academico_codigo = d.grado_academico_codigo
where b.persona_codigo=