1：在mysql查询中实现N.

Assume 2 columns in table state_info.

state       |  district
------------+---------------
Karnataka   |  Bangalore
Karnataka   |  Belgium
Karnataka   |  Mysore
Mumbai      |  Sandra
Mumbai      |  Madeira

I want to output them in a single column

Karnataka
Bangalore
Belgium
Mysore

Mumbai
Sandra
Madeira

state below that its dist ,again state below its dist

Use

SELECT CONCAT(state, ', ', district) FROM state_info;

to get

Karnataka, Bangalore
Karnataka, Belgium
Karnataka, Mysore
Mumbai, Sandra
Mumbai, Madeira

You can do like this

Select Distinct(state) from Table1
UNION 
Select Distinct(district) from Table1;

the result will be

Bangalore
Belgium
Mysore
Sandra
Madeira
Karnataka
Mumbai

select * from (
 Select Distinct(state) as data from Table1
 UNION 
 Select Distinct(district) as data from Table1;
) order by  data