select t1.企业代码,t1.企业名称,t1.主行业代码,
(select t3.行业名称 from t3 where t1.主行业代码 = t3.行业代码) 行业名称,
t2.次行业01代码, (select t3.行业名称 from t3 where t2.次行业01代码 = t3.行业代码) 次行业01名称,
t2.次行业02代码, (select t3.行业名称 from t3 where t2.次行业02代码 = t3.行业代码) 次行业02名称,
t2.次行业03代码, (select t3.行业名称 from t3 where t2.次行业03代码 = t3.行业代码) 次行业03名称
from t1,t2
where t1.企业代码 = t2.企业代码