MySQL语法查询，用于将列合并为一个

Question

Please. Help me. How to combine records of multiple columns in one new column ? In my table I have 3 columns named PIO1, PIO2 and PIO3. So I want to combine the records of all three columns in one column.

This is my Column [1]: http://i.stack.imgur.com/JOnH4.png and this is the output what I want to show [2]: http://i.stack.imgur.com/aKUmB.png

Answer 1

If you need records of all columns in same column, use UNION ALL

SELECT PIO FROM
(
    SELECT id as 'id', PIO1 as 'PIO' FROM tbl_name
    UNION ALL
    SELECT id as 'id', PIO2 as 'PIO' FROM tbl_name
    UNION ALL
    SELECT id as 'id', PIO3 as 'PIO' FROM tbl_name
) a 
ORDER BY id

Answer 2

Try this

alter table <tablename> add combocolumn varchar(3000);

update <tablename> set combocolumn = concat (PO1,PO2,PO3);

This assumes that "combine" means concatenate without adding a separator, and that 3000 characters will be enough.