@test	@`select`	@TEST	@not_used
1	2	3	NULL
@test_int	@test_double	@test_string	@test_string2	@select
10	0.00	abcdeghi	abcdefghij	NULL
@test_int	@test_double	@test_string	@test_string2
hello	hello	hello	hello
@test_int	@test_double	@test_string	@test_string2
hellohello	hellohello	hellohello	hellohello
@test_int	@test_double	@test_string	@test_string2
NULL	NULL	NULL	NULL
@t1:=(@t2:=1)+@t3:=4	@t1	@t2	@t3
5	5	1	4