[MySQL] 컬럼 & 필드 합치기 concat(), group_concat()

concat()

 

ex ) 

 

concat(column, column)

 

item_table​

idx	category1	category2	category3
5	1	2	3

 

 

select idx, concat(category1, "/", category2, "/", category3) as merge_column 

from item_table 

where idx = 5 

 

idx	merge_column
5	1/2/3

 

 

 

group_concat()

 

ex)

 

group_concat(field saparator '구분자')

 

item_table

idx	category
5	1
5	2
5	3

 

select idx, group_concat(category saparator '/') as group_concat

from item_table

where idx= 5

 

idx	group_concat
5	1/2/3