如何合并列

Question

 projectid1 project2 name
  3           3       aa
  4                    bb
               4       a
如何把projectid1，projectid2 转换成
 projectid name
   3         aa
   4         bb 
   4          a
   

Answer 1

数据是这样么？ projectid1 project2 name
  3         3        aa
  4        null      bb
  4        null      a

Answer 2

需要怎么来合并  貌似看不出啥规律来  按lz的提供的数据  直接查询projectid1和name2列就行了 

Answer 3

SELECT PROJECTID1,NAME FROM TABLE
UNION
SELECT PROJECT2,NAME FROM TABLE

Answer 4

select concat(projectid1,projectid2) as  projectidname from dual;

Answer 5

select nvl(projectid1,projectid2) projectid,name from table_name
是要表达这个意思吗？

Answer 6

select concat(projectid1,projectid2) as projectid || name from dual;