c	d
1	
2	a
3	b
a	b
4	e
5	f
6	g
a	b
4	e
5	f
6	g
a	b
4	e
5	f
6	g
c	d
1	
2	a
3	b
c	d	e
1		2
2	a	2
3	b	2
CONCAT_WS(pkCrash, strCrash)
1
id	val	elt(two.val,'one','two')
1	1	one
2	1	one
4	2	two