MySQL数据库

开发平台：

Visual C++

distinct.result：源码内容

							id
NULL
-1
0
1
2
3
4
5
6
7
8
9
10
id	facility
NULL	NULL
-1	
0	
1	/L
2	A01
3	ANC
4	F01
5	FBX
6	MT
7	P
8	RV
9	SRV
10	VMT
id-5	facility
NULL	NULL
-6	
-5	
-4	/L
-3	A01
-2	ANC
-1	F01
0	FBX
1	MT
2	P
3	RV
4	SRV
5	VMT
id	concat(facility)
NULL	NULL
-1	
0	
1	/L
2	A01
3	ANC
4	F01
5	FBX
6	MT
7	P
8	RV
9	SRV
10	VMT
a	max(id)	b
10	10	VMT
9	9	SRV
8	8	RV
7	7	P
6	6	MT
5	5	FBX
4	4	F01
3	3	ANC
2	2	A01
1	1	/L
-1	-1	
0	0	
NULL	NULL	NULL
grp	count(*)
0	7
1	6
FACILITY
NULL
/L
A01
ANC
F01
FBX
MT
P
RV
SRV
VMT
FACILITY
NULL
/L
A01
ANC
F01
FBX
MT
P
RV
SRV
VMT
count(*)
12
count(facility)
12
count(*)
13
count(*)
1
count(*)
0
count(*)
12
count(*)
1
count(*)
12
UserId
UserId
UserId
UserId
b
1
table	type	possible_keys	key	key_len	ref	rows	Extra
t3	index	a	a	5	NULL	6	Using index; Using temporary
t2	index	a	a	4	NULL	5	Using index; Distinct
t1	eq_ref	PRIMARY	PRIMARY	4	t2.a	1	where used; Distinct
a
1
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	index	PRIMARY	PRIMARY	4	NULL	2	Using index; Using temporary
t3	ref	a	a	5	t1.a	10	Using index; Distinct
a
1
2
1
1
name
aa
ab
name
aa
ab
1
1
key_link_id	link
NULL	NULL
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	index	id	id	4	NULL	2	Using index; Using temporary
t2	index	id	id	8	NULL	1	Using index; Distinct
t3	index	id	id	8	NULL	1	Using index; Distinct
j_lj_t2	index	id	id	4	NULL	2	where used; Using index; Distinct
t2_lj	index	id	id	8	NULL	1	where used; Using index; Distinct
j_lj_t3	index	id	id	4	NULL	2	where used; Using index; Distinct
t3_lj	index	id	id	8	NULL	1	where used; Using index; Distinct
id
2
a	sec_to_time(sum(time_to_sec(t)))
1	00:06:15
1	00:36:30
1	00:36:30
a	sec_to_time(sum(time_to_sec(t)))
1	00:06:15
1	00:36:30
a	sec_to_time(sum(time_to_sec(t)))
1	00:06:15
1	00:36:30
1	00:36:30
a	sec_to_time(sum(time_to_sec(t)))
1	00:06:15
1	00:36:30

						