b4rt3kk b4rt3kk - 6 months ago 8
SQL Question

GROUP BY but get all values from other column

I''ll explain what I need to do on example. First of all, we have a simple table like this one, named table:

id | name
===+=====
1 | foo
1 | bar
1 | foobar
2 | foo
2 | bar
2 | foobar


Now the query:

SELECT t.* FROM table t GROUP BY t.id


Will get us result similar to this one:

id | name
===+=====
1 | foo
2 | foo


But is it possible, to collect all values of name to have result like this?

id | name
===+=================
1 | foo, bar, foobar
2 | foo, bar, foobar

Answer

Using MySQL you can use GROUP_CONCAT(expr)

This function returns a string result with the concatenated non-NULL values from a group. It returns NULL if there are no non-NULL values. The full syntax is as follows:

GROUP_CONCAT([DISTINCT] expr [,expr ...]
             [ORDER BY {unsigned_integer | col_name | expr}
                 [ASC | DESC] [,col_name ...]]
             [SEPARATOR str_val])

Something like

SELECT ID, GROUP_CONCAT(name) GroupedName
FROM Table1
GROUP BY ID

SQL Fiddle DEMO