1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
|
drop table if exists t1,t2,t3;
CREATE TABLE t1 (id int,facility char(20));
CREATE TABLE t2 (facility char(20));
INSERT INTO t1 VALUES (NULL,NULL);
INSERT INTO t1 VALUES (-1,'');
INSERT INTO t1 VALUES (0,'');
INSERT INTO t1 VALUES (1,'/L');
INSERT INTO t1 VALUES (2,'A01');
INSERT INTO t1 VALUES (3,'ANC');
INSERT INTO t1 VALUES (4,'F01');
INSERT INTO t1 VALUES (5,'FBX');
INSERT INTO t1 VALUES (6,'MT');
INSERT INTO t1 VALUES (7,'P');
INSERT INTO t1 VALUES (8,'RV');
INSERT INTO t1 VALUES (9,'SRV');
INSERT INTO t1 VALUES (10,'VMT');
INSERT INTO t2 SELECT DISTINCT FACILITY FROM t1;
select id from t1 group by id;
id
NULL
-1
0
1
2
3
4
5
6
7
8
9
10
select * from t1 order by id;
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
select id-5,facility from t1 order by "id-5";
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
select id,concat(facility) from t1 group by id ;
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
select id+0 as a,max(id),concat(facility) as b from t1 group by a order by b desc,a;
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
select id >= 0 and id <= 5 as grp,count(*) from t1 group by grp;
grp count(*)
NULL 1
0 6
1 6
SELECT DISTINCT FACILITY FROM t1;
FACILITY
NULL
/L
A01
ANC
F01
FBX
MT
P
RV
SRV
VMT
SELECT FACILITY FROM t2;
FACILITY
NULL
/L
A01
ANC
F01
FBX
MT
P
RV
SRV
VMT
SELECT count(*) from t1,t2 where t1.facility=t2.facility;
count(*)
12
select count(facility) from t1;
count(facility)
12
select count(*) from t1;
count(*)
13
select count(*) from t1 where facility IS NULL;
count(*)
1
select count(*) from t1 where facility = NULL;
count(*)
0
select count(*) from t1 where facility IS NOT NULL;
count(*)
12
select count(*) from t1 where id IS NULL;
count(*)
1
select count(*) from t1 where id IS NOT NULL;
count(*)
12
drop table t1,t2;
CREATE TABLE t1 (UserId int(11) DEFAULT '0' NOT NULL);
INSERT INTO t1 VALUES (20);
INSERT INTO t1 VALUES (27);
SELECT UserId FROM t1 WHERE Userid=22;
UserId
SELECT UserId FROM t1 WHERE UserId=22 group by Userid;
UserId
SELECT DISTINCT UserId FROM t1 WHERE UserId=22 group by Userid;
UserId
SELECT DISTINCT UserId FROM t1 WHERE UserId=22;
UserId
drop table t1;
CREATE TABLE t1 (a int(10) unsigned not null primary key,b int(10) unsigned);
INSERT INTO t1 VALUES (1,1),(2,1),(3,1),(4,1);
CREATE TABLE t2 (a int(10) unsigned not null, key (A));
INSERT INTO t2 VALUES (1),(2);
CREATE TABLE t3 (a int(10) unsigned, key(A), b text);
INSERT INTO t3 VALUES (1,'1'),(2,'2');
SELECT DISTINCT t3.b FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;
b
1
INSERT INTO t2 values (1),(2),(3);
INSERT INTO t3 VALUES (1,'1'),(2,'2'),(1,'1'),(2,'2');
explain SELECT distinct t3.a FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 4 Using temporary
1 SIMPLE t3 ref a a 5 test.t1.b 2 Using index
1 SIMPLE t2 index a a 4 NULL 5 Using where; Using index; Distinct; Using join buffer
SELECT distinct t3.a FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;
a
1
create temporary table t4 select * from t3;
insert into t3 select * from t4;
insert into t4 select * from t3;
insert into t3 select * from t4;
insert into t4 select * from t3;
insert into t3 select * from t4;
insert into t4 select * from t3;
insert into t3 select * from t4;
explain select distinct t1.a from t1,t3 where t1.a=t3.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index PRIMARY PRIMARY 4 NULL 4 Using index; Using temporary
1 SIMPLE t3 ref a a 5 test.t1.a 11 Using index; Distinct
select distinct t1.a from t1,t3 where t1.a=t3.a;
a
1
2
select distinct 1 from t1,t3 where t1.a=t3.a;
1
1
explain SELECT distinct t1.a from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 4 Using index
explain SELECT distinct t1.a from t1 order by a desc;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 4 Using index
explain SELECT t1.a from t1 group by a order by a desc;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 4 Using index
explain SELECT distinct t1.a from t1 order by a desc limit 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 1 Using index
explain SELECT distinct a from t3 order by a desc limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index NULL a 5 NULL 40 Using index
explain SELECT distinct a,b from t3 order by a+1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 ALL NULL NULL NULL NULL 204 Using temporary; Using filesort
explain SELECT distinct a,b from t3 order by a limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index NULL a 5 NULL 2 Using temporary
explain SELECT a,b from t3 group by a,b order by a+1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 ALL NULL NULL NULL NULL 204 Using temporary; Using filesort
drop table t1,t2,t3,t4;
CREATE TABLE t1 (name varchar(255));
INSERT INTO t1 VALUES ('aa'),('ab'),('ac'),('ad'),('ae');
SELECT DISTINCT * FROM t1 LIMIT 2;
name
aa
ab
SELECT DISTINCT name FROM t1 LIMIT 2;
name
aa
ab
SELECT DISTINCT 1 FROM t1 LIMIT 2;
1
1
drop table t1;
CREATE TABLE t1 (
ID int(11) NOT NULL auto_increment,
NAME varchar(75) DEFAULT '' NOT NULL,
LINK_ID int(11) DEFAULT '0' NOT NULL,
PRIMARY KEY (ID),
KEY NAME (NAME),
KEY LINK_ID (LINK_ID)
);
INSERT INTO t1 (ID, NAME, LINK_ID) VALUES (1,'Mike',0),(2,'Jack',0),(3,'Bill',0);
CREATE TABLE t2 (
ID int(11) NOT NULL auto_increment,
NAME varchar(150) DEFAULT '' NOT NULL,
PRIMARY KEY (ID),
KEY NAME (NAME)
);
SELECT DISTINCT
t2.id AS key_link_id,
t2.name AS link
FROM t1
LEFT JOIN t2 ON t1.link_id=t2.id
GROUP BY t1.id
ORDER BY link;
key_link_id link
NULL NULL
drop table t1,t2;
create table t1 (
id int not null,
name tinytext not null,
unique (id)
);
create table t2 (
id int not null,
idx int not null,
unique (id, idx)
);
create table t3 (
id int not null,
idx int not null,
unique (id, idx)
);
insert into t1 values (1,'yes'), (2,'no');
insert into t2 values (1,1);
insert into t3 values (1,1);
EXPLAIN
SELECT DISTINCT
t1.id
from
t1
straight_join
t2
straight_join
t3
straight_join
t1 as j_lj_t2 left join t2 as t2_lj
on j_lj_t2.id=t2_lj.id
straight_join
t1 as j_lj_t3 left join t3 as t3_lj
on j_lj_t3.id=t3_lj.id
WHERE
((t1.id=j_lj_t2.id AND t2_lj.id IS NULL) OR (t1.id=t2.id AND t2.idx=2))
AND ((t1.id=j_lj_t3.id AND t3_lj.id IS NULL) OR (t1.id=t3.id AND t3.idx=2));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index id id 4 NULL 2 Using index; Using temporary
1 SIMPLE t2 index id id 8 NULL 1 Using index; Distinct; Using join buffer
1 SIMPLE t3 index id id 8 NULL 1 Using index; Distinct; Using join buffer
1 SIMPLE j_lj_t2 index id id 4 NULL 2 Using where; Using index; Distinct; Using join buffer
1 SIMPLE t2_lj ref id id 4 test.j_lj_t2.id 1 Using where; Using index; Distinct
1 SIMPLE j_lj_t3 index id id 4 NULL 2 Using where; Using index; Distinct; Using join buffer
1 SIMPLE t3_lj ref id id 4 test.j_lj_t3.id 1 Using where; Using index; Distinct
SELECT DISTINCT
t1.id
from
t1
straight_join
t2
straight_join
t3
straight_join
t1 as j_lj_t2 left join t2 as t2_lj
on j_lj_t2.id=t2_lj.id
straight_join
t1 as j_lj_t3 left join t3 as t3_lj
on j_lj_t3.id=t3_lj.id
WHERE
((t1.id=j_lj_t2.id AND t2_lj.id IS NULL) OR (t1.id=t2.id AND t2.idx=2))
AND ((t1.id=j_lj_t3.id AND t3_lj.id IS NULL) OR (t1.id=t3.id AND t3.idx=2));
id
2
drop table t1,t2,t3;
create table t1 (a int not null, b int not null, t time);
insert into t1 values (1,1,"00:06:15"),(1,2,"00:06:15"),(1,2,"00:30:15"),(1,3,"00:06:15"),(1,3,"00:30:15");
select a,sec_to_time(sum(time_to_sec(t))) from t1 group by a,b;
a sec_to_time(sum(time_to_sec(t)))
1 00:06:15
1 00:36:30
1 00:36:30
select distinct a,sec_to_time(sum(time_to_sec(t))) from t1 group by a,b;
a sec_to_time(sum(time_to_sec(t)))
1 00:06:15
1 00:36:30
create table t2 (a int not null primary key, b int);
insert into t2 values (1,1),(2,2),(3,3);
select t1.a,sec_to_time(sum(time_to_sec(t))) from t1 left join t2 on (t1.b=t2.a) group by t1.a,t2.b;
a sec_to_time(sum(time_to_sec(t)))
1 00:06:15
1 00:36:30
1 00:36:30
select distinct t1.a,sec_to_time(sum(time_to_sec(t))) from t1 left join t2 on (t1.b=t2.a) group by t1.a,t2.b;
a sec_to_time(sum(time_to_sec(t)))
1 00:06:15
1 00:36:30
drop table t1,t2;
create table t1 (a int not null,b char(5), c text);
insert into t1 (a) values (1),(2),(3),(4),(1),(2),(3),(4);
select distinct a from t1 group by b,a having a > 2 order by a desc;
a
4
3
select distinct a,c from t1 group by b,c,a having a > 2 order by a desc;
a c
4 NULL
3 NULL
drop table t1;
create table t1 (a char(1), key(a)) engine=myisam;
insert into t1 values('1'),('1');
select * from t1 where a >= '1';
a
1
1
select distinct a from t1 order by a desc;
a
1
select distinct a from t1 where a >= '1' order by a desc;
a
1
drop table t1;
CREATE TABLE t1 (email varchar(50), infoID BIGINT, dateentered DATETIME);
CREATE TABLE t2 (infoID BIGINT, shipcode varchar(10));
INSERT INTO t1 (email, infoID, dateentered) VALUES
('test1@testdomain.com', 1, '2002-07-30 22:56:38'),
('test1@testdomain.com', 1, '2002-07-27 22:58:16'),
('test2@testdomain.com', 1, '2002-06-19 15:22:19'),
('test2@testdomain.com', 2, '2002-06-18 14:23:47'),
('test3@testdomain.com', 1, '2002-05-19 22:17:32');
INSERT INTO t2(infoID, shipcode) VALUES
(1, 'Z001'),
(2, 'R002');
SELECT DISTINCTROW email, shipcode FROM t1, t2 WHERE t1.infoID=t2.infoID;
email shipcode
test1@testdomain.com Z001
test2@testdomain.com Z001
test2@testdomain.com R002
test3@testdomain.com Z001
SELECT DISTINCTROW email FROM t1 ORDER BY dateentered DESC;
email
test1@testdomain.com
test2@testdomain.com
test3@testdomain.com
SELECT DISTINCTROW email, shipcode FROM t1, t2 WHERE t1.infoID=t2.infoID ORDER BY dateentered DESC;
email shipcode
test1@testdomain.com Z001
test2@testdomain.com Z001
test2@testdomain.com R002
test3@testdomain.com Z001
drop table t1,t2;
CREATE TABLE t1 (privatemessageid int(10) unsigned NOT NULL auto_increment, folderid smallint(6) NOT NULL default '0', userid int(10) unsigned NOT NULL default '0', touserid int(10) unsigned NOT NULL default '0', fromuserid int(10) unsigned NOT NULL default '0', title varchar(250) NOT NULL default '', message mediumtext NOT NULL, dateline int(10) unsigned NOT NULL default '0', showsignature smallint(6) NOT NULL default '0', iconid smallint(5) unsigned NOT NULL default '0', messageread smallint(6) NOT NULL default '0', readtime int(10) unsigned NOT NULL default '0', receipt smallint(6) unsigned NOT NULL default '0', deleteprompt smallint(6) unsigned NOT NULL default '0', multiplerecipients smallint(6) unsigned NOT NULL default '0', PRIMARY KEY (privatemessageid), KEY userid (userid)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (128,0,33,33,8,':D','',996121863,1,0,2,996122850,2,0,0);
CREATE TABLE t2 (userid int(10) unsigned NOT NULL auto_increment, usergroupid smallint(5) unsigned NOT NULL default '0', username varchar(50) NOT NULL default '', password varchar(50) NOT NULL default '', email varchar(50) NOT NULL default '', styleid smallint(5) unsigned NOT NULL default '0', parentemail varchar(50) NOT NULL default '', coppauser smallint(6) NOT NULL default '0', homepage varchar(100) NOT NULL default '', icq varchar(20) NOT NULL default '', aim varchar(20) NOT NULL default '', yahoo varchar(20) NOT NULL default '', signature mediumtext NOT NULL, adminemail smallint(6) NOT NULL default '0', showemail smallint(6) NOT NULL default '0', invisible smallint(6) NOT NULL default '0', usertitle varchar(250) NOT NULL default '', customtitle smallint(6) NOT NULL default '0', joindate int(10) unsigned NOT NULL default '0', cookieuser smallint(6) NOT NULL default '0', daysprune smallint(6) NOT NULL default '0', lastvisit int(10) unsigned NOT NULL default '0', lastactivity int(10) unsigned NOT NULL default '0', lastpost int(10) unsigned NOT NULL default '0', posts smallint(5) unsigned NOT NULL default '0', timezoneoffset varchar(4) NOT NULL default '', emailnotification smallint(6) NOT NULL default '0', buddylist mediumtext NOT NULL, ignorelist mediumtext NOT NULL, pmfolders mediumtext NOT NULL, receivepm smallint(6) NOT NULL default '0', emailonpm smallint(6) NOT NULL default '0', pmpopup smallint(6) NOT NULL default '0', avatarid smallint(6) NOT NULL default '0', avatarrevision int(6) unsigned NOT NULL default '0', options smallint(6) NOT NULL default '15', birthday date NOT NULL default '0000-00-00', maxposts smallint(6) NOT NULL default '-1', startofweek smallint(6) NOT NULL default '1', ipaddress varchar(20) NOT NULL default '', referrerid int(10) unsigned NOT NULL default '0', nosessionhash smallint(6) NOT NULL default '0', autorefresh smallint(6) NOT NULL default '-1', messagepopup tinyint(2) NOT NULL default '0', inforum smallint(5) unsigned NOT NULL default '0', ratenum smallint(5) unsigned NOT NULL default '0', ratetotal smallint(5) unsigned NOT NULL default '0', allowrate smallint(5) unsigned NOT NULL default '1', PRIMARY KEY (userid), KEY usergroupid (usergroupid), KEY username (username), KEY inforum (inforum)) ENGINE=MyISAM;
INSERT INTO t2 VALUES (33,6,'Kevin','0','kevin@stileproject.com',1,'',0,'http://www.stileproject.com','','','','',1,1,0,'Administrator',0,996120694,1,-1,1030996168,1031027028,1030599436,36,'-6',0,'','','',1,0,1,0,0,15,'0000-00-00',-1,1,'64.0.0.0',0,1,-1,0,0,4,19,1);
SELECT DISTINCT t1.*, t2.* FROM t1 LEFT JOIN t2 ON (t2.userid = t1.touserid);
privatemessageid folderid userid touserid fromuserid title message dateline showsignature iconid messageread readtime receipt deleteprompt multiplerecipients userid usergroupid username password email styleid parentemail coppauser homepage icq aim yahoo signature adminemail showemail invisible usertitle customtitle joindate cookieuser daysprune lastvisit lastactivity lastpost posts timezoneoffset emailnotification buddylist ignorelist pmfolders receivepm emailonpm pmpopup avatarid avatarrevision options birthday maxposts startofweek ipaddress referrerid nosessionhash autorefresh messagepopup inforum ratenum ratetotal allowrate
128 0 33 33 8 :D 996121863 1 0 2 996122850 2 0 0 33 6 Kevin 0 kevin@stileproject.com 1 0 http://www.stileproject.com 1 1 0 Administrator 0 996120694 1 -1 1030996168 1031027028 1030599436 36 -6 0 1 0 1 0 0 15 0000-00-00 -1 1 64.0.0.0 0 1 -1 0 0 4 19 1
DROP TABLE t1,t2;
CREATE TABLE t1 (a int primary key, b int, c int);
INSERT t1 VALUES (1,2,3);
CREATE TABLE t2 (a int primary key, b int, c int);
INSERT t2 VALUES (3,4,5);
SELECT DISTINCT t1.a, t2.b FROM t1, t2 WHERE t1.a=1 ORDER BY t2.c;
a b
1 4
DROP TABLE t1,t2;
CREATE table t1 ( `id` int(11) NOT NULL auto_increment, `name` varchar(50) NOT NULL default '', PRIMARY KEY (`id`)) ENGINE=MyISAM AUTO_INCREMENT=3 ;
INSERT INTO t1 VALUES (1, 'aaaaa');
INSERT INTO t1 VALUES (3, 'aaaaa');
INSERT INTO t1 VALUES (2, 'eeeeeee');
select distinct left(name,1) as name from t1;
name
a
e
drop table t1;
CREATE TABLE t1 (
ID int(11) NOT NULL auto_increment,
NAME varchar(75) DEFAULT '' NOT NULL,
LINK_ID int(11) DEFAULT '0' NOT NULL,
PRIMARY KEY (ID),
KEY NAME (NAME),
KEY LINK_ID (LINK_ID)
);
INSERT INTO t1 (ID, NAME, LINK_ID) VALUES (1,'Mike',0);
INSERT INTO t1 (ID, NAME, LINK_ID) VALUES (2,'Jack',0);
INSERT INTO t1 (ID, NAME, LINK_ID) VALUES (3,'Bill',0);
CREATE TABLE t2 (
ID int(11) NOT NULL auto_increment,
NAME varchar(150) DEFAULT '' NOT NULL,
PRIMARY KEY (ID),
KEY NAME (NAME)
);
SELECT DISTINCT
t2.id AS key_link_id,
t2.name AS link
FROM t1
LEFT JOIN t2 ON t1.link_id=t2.id
GROUP BY t1.id
ORDER BY link;
key_link_id link
NULL NULL
drop table t1,t2;
CREATE TABLE t1 (
html varchar(5) default NULL,
rin int(11) default '0',
rout int(11) default '0'
) ENGINE=MyISAM;
INSERT INTO t1 VALUES ('1',1,0);
SELECT DISTINCT html,SUM(rout)/(SUM(rin)+1) as 'prod' FROM t1 GROUP BY rin;
html prod
1 0.0000
drop table t1;
CREATE TABLE t1 (a int);
INSERT INTO t1 VALUES (1),(2),(3),(4),(5);
SELECT DISTINCT a, 1 FROM t1;
a 1
1 1
2 1
3 1
4 1
5 1
SELECT DISTINCT 1, a FROM t1;
1 a
1 1
1 2
1 3
1 4
1 5
CREATE TABLE t2 (a int, b int);
INSERT INTO t2 VALUES (1,1),(2,2),(2,3),(2,4),(3,5);
SELECT DISTINCT a, b, 2 FROM t2;
a b 2
1 1 2
2 2 2
2 3 2
2 4 2
3 5 2
SELECT DISTINCT 2, a, b FROM t2;
2 a b
2 1 1
2 2 2
2 2 3
2 2 4
2 3 5
SELECT DISTINCT a, 2, b FROM t2;
a 2 b
1 2 1
2 2 2
2 2 3
2 2 4
3 2 5
DROP TABLE t1,t2;
CREATE TABLE t1(a INT PRIMARY KEY, b INT);
INSERT INTO t1 VALUES (1,1), (2,1), (3,1);
EXPLAIN SELECT DISTINCT a FROM t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 3 Using index
EXPLAIN SELECT DISTINCT a,b FROM t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
EXPLAIN SELECT DISTINCT t1_1.a, t1_1.b FROM t1 t1_1, t1 t1_2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_1 ALL NULL NULL NULL NULL 3 Using temporary
1 SIMPLE t1_2 index NULL PRIMARY 4 NULL 3 Using index; Distinct; Using join buffer
EXPLAIN SELECT DISTINCT t1_1.a, t1_1.b FROM t1 t1_1, t1 t1_2
WHERE t1_1.a = t1_2.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1_1 ALL PRIMARY NULL NULL NULL 3 Using temporary
1 SIMPLE t1_2 eq_ref PRIMARY PRIMARY 4 test.t1_1.a 1 Using index; Distinct
EXPLAIN SELECT a FROM t1 GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 3 Using index
EXPLAIN SELECT a,b FROM t1 GROUP BY a,b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using filesort
EXPLAIN SELECT DISTINCT a,b FROM t1 GROUP BY a,b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using filesort
CREATE TABLE t2(a INT, b INT NOT NULL, c INT NOT NULL, d INT,
PRIMARY KEY (a,b));
INSERT INTO t2 VALUES (1,1,1,50), (1,2,3,40), (2,1,3,4);
EXPLAIN SELECT DISTINCT a FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL PRIMARY 8 NULL 3 Using index
EXPLAIN SELECT DISTINCT a,a FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL PRIMARY 8 NULL 3 Using index
EXPLAIN SELECT DISTINCT b,a FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL PRIMARY 8 NULL 3 Using index
EXPLAIN SELECT DISTINCT a,c FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 3 Using temporary
EXPLAIN SELECT DISTINCT c,a,b FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 3
EXPLAIN SELECT DISTINCT a,b,d FROM t2 GROUP BY c,b,d;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 3 Using temporary; Using filesort
CREATE UNIQUE INDEX c_b_unq ON t2 (c,b);
EXPLAIN SELECT DISTINCT a,b,d FROM t2 GROUP BY c,b,d;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 3 Using filesort
DROP TABLE t1,t2;
create table t1 (id int, dsc varchar(50));
insert into t1 values (1, "line number one"), (2, "line number two"), (3, "line number three");
select distinct id, IFNULL(dsc, '-') from t1;
id IFNULL(dsc, '-')
1 line number one
2 line number two
3 line number three
drop table t1;
CREATE TABLE t1 (a int primary key, b int);
INSERT INTO t1 (a,b) values (1,1), (2,3), (3,2);
explain SELECT DISTINCT a, b FROM t1 ORDER BY b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using filesort
SELECT DISTINCT a, b FROM t1 ORDER BY b;
a b
1 1
3 2
2 3
DROP TABLE t1;
CREATE TABLE t1 (
ID int(11) NOT NULL auto_increment,
x varchar(20) default NULL,
y decimal(10,0) default NULL,
PRIMARY KEY (ID),
KEY (y)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
INSERT INTO t1 VALUES
(1,'ba','-1'),
(2,'ba','1150'),
(306,'ba','-1'),
(307,'ba','1150'),
(611,'ba','-1'),
(612,'ba','1150');
select count(distinct x,y) from t1;
count(distinct x,y)
2
select count(distinct concat(x,y)) from t1;
count(distinct concat(x,y))
2
drop table t1;
CREATE TABLE t1 (a INT, b INT, PRIMARY KEY (a,b));
INSERT INTO t1 VALUES (1, 101);
INSERT INTO t1 SELECT a + 1, a + 101 FROM t1;
INSERT INTO t1 SELECT a + 2, a + 102 FROM t1;
INSERT INTO t1 SELECT a + 4, a + 104 FROM t1;
INSERT INTO t1 SELECT a + 8, a + 108 FROM t1;
EXPLAIN SELECT DISTINCT a,a FROM t1 WHERE b < 12 ORDER BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 8 NULL 16 Using where; Using index
SELECT DISTINCT a,a FROM t1 WHERE b < 12 ORDER BY a;
a a
DROP TABLE t1;
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (id INT NOT NULL, fruit_id INT NOT NULL, fruit_name varchar(20)
default NULL);
INSERT INTO t1 VALUES (1,1,'ORANGE');
INSERT INTO t1 VALUES (2,2,'APPLE');
INSERT INTO t1 VALUES (3,2,'APPLE');
INSERT INTO t1 VALUES (4,3,'PEAR');
SELECT DISTINCT fruit_id, fruit_name INTO @v1, @v2 FROM t1 WHERE fruit_name =
'APPLE';
SELECT @v1, @v2;
@v1 @v2
2 APPLE
SELECT DISTINCT fruit_id, fruit_name INTO @v3, @v4 FROM t1 GROUP BY fruit_id,
fruit_name HAVING fruit_name = 'APPLE';
SELECT @v3, @v4;
@v3 @v4
2 APPLE
SELECT DISTINCT @v5:= fruit_id, @v6:= fruit_name INTO @v7, @v8 FROM t1 WHERE
fruit_name = 'APPLE';
SELECT @v5, @v6, @v7, @v8;
@v5 @v6 @v7 @v8
2 APPLE 2 APPLE
SELECT DISTINCT @v5 + fruit_id, CONCAT(@v6, fruit_name) INTO @v9, @v10 FROM t1
WHERE fruit_name = 'APPLE';
SELECT @v5, @v6, @v7, @v8, @v9, @v10;
@v5 @v6 @v7 @v8 @v9 @v10
2 APPLE 2 APPLE 4 APPLEAPPLE
SELECT DISTINCT @v11:= @v5 + fruit_id, @v12:= CONCAT(@v6, fruit_name) INTO
@v13, @v14 FROM t1 WHERE fruit_name = 'APPLE';
SELECT @v11, @v12, @v13, @v14;
@v11 @v12 @v13 @v14
4 APPLEAPPLE 4 APPLEAPPLE
SELECT DISTINCT @v13, @v14 INTO @v15, @v16 FROM t1 WHERE fruit_name = 'APPLE';
SELECT @v15, @v16;
@v15 @v16
4 APPLEAPPLE
SELECT DISTINCT 2 + 2, 'Bob' INTO @v17, @v18 FROM t1 WHERE fruit_name =
'APPLE';
SELECT @v17, @v18;
@v17 @v18
4 Bob
DROP TABLE IF EXISTS t2;
CREATE TABLE t2 (fruit_id INT NOT NULL, fruit_name varchar(20)
default NULL);
SELECT DISTINCT fruit_id, fruit_name INTO OUTFILE
'../../tmp/data1.tmp' FROM t1 WHERE fruit_name = 'APPLE';
LOAD DATA INFILE '../../tmp/data1.tmp' INTO TABLE t2;
SELECT DISTINCT @v19:= fruit_id, @v20:= fruit_name INTO OUTFILE
'../../tmp/data2.tmp' FROM t1 WHERE fruit_name = 'APPLE';
LOAD DATA INFILE '../../tmp/data2.tmp' INTO TABLE t2;
SELECT @v19, @v20;
@v19 @v20
2 APPLE
SELECT * FROM t2;
fruit_id fruit_name
2 APPLE
2 APPLE
DROP TABLE t1;
DROP TABLE t2;
CREATE TABLE t1 (a CHAR(1));
INSERT INTO t1 VALUES('A'), (0);
SELECT a FROM t1 WHERE a=0;
a
A
0
Warnings:
Warning 1292 Truncated incorrect DOUBLE value: 'A'
SELECT DISTINCT a FROM t1 WHERE a=0;
a
A
0
Warnings:
Warning 1292 Truncated incorrect DOUBLE value: 'A'
DROP TABLE t1;
CREATE TABLE t1 (a DATE);
INSERT INTO t1 VALUES ('1972-07-29'), ('1972-02-06');
EXPLAIN SELECT (SELECT DISTINCT a FROM t1 WHERE a = '2002-08-03');
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
2 SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
EXPLAIN SELECT (SELECT DISTINCT ADDDATE(a,1) FROM t1
WHERE ADDDATE(a,1) = '2002-08-03');
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
2 SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
CREATE TABLE t2 (a CHAR(5) CHARACTER SET latin1 COLLATE latin1_general_ci);
INSERT INTO t2 VALUES (0xf6);
INSERT INTO t2 VALUES ('oe');
SELECT COUNT(*) FROM (SELECT DISTINCT a FROM t2) dt;
COUNT(*)
2
SELECT COUNT(*) FROM
(SELECT DISTINCT a FROM t2 WHERE a='oe' COLLATE latin1_german2_ci) dt;
COUNT(*)
2
DROP TABLE t1, t2;
CREATE TABLE t1 (a INT, UNIQUE (a));
INSERT INTO t1 VALUES (4),(null),(2),(1),(null),(3);
EXPLAIN SELECT DISTINCT a FROM t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL a 5 NULL 6 Using index
SELECT DISTINCT a FROM t1;
a
NULL
1
2
3
4
EXPLAIN SELECT a FROM t1 GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL a 5 NULL 6 Using index
SELECT a FROM t1 GROUP BY a;
a
NULL
1
2
3
4
DROP TABLE t1;
CREATE TABLE t1 (a INT, b INT);
INSERT INTO t1 VALUES(1,1),(1,2),(1,3);
SELECT DISTINCT a, b FROM t1;
a b
1 1
1 2
1 3
SELECT DISTINCT a, a, b FROM t1;
a a b
1 1 1
1 1 2
1 1 3
DROP TABLE t1;
End of 5.0 tests
CREATE TABLE t1(a INT, b INT, c INT, d INT, e INT,
PRIMARY KEY(a,b,c,d,e),
KEY(a,b,d,c)
);
INSERT INTO t1(a, b, c) VALUES (1, 1, 1),
(1, 1, 2),
(1, 1, 3),
(1, 2, 1),
(1, 2, 2),
(1, 2, 3);
EXPLAIN SELECT DISTINCT a, b, d, c FROM t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL PRIMARY 16 NULL 7 Using index for group-by; Using temporary
SELECT DISTINCT a, b, d, c FROM t1;
a b d c
1 1 0 1
1 1 0 2
1 1 0 3
1 2 0 1
1 2 0 2
1 2 0 3
DROP TABLE t1;
#
# Bug #46159: simple query that never returns
#
SET @old_max_heap_table_size = @@max_heap_table_size;
SET @@max_heap_table_size = 16384;
SET @old_sort_buffer_size = @@sort_buffer_size;
SET @@sort_buffer_size = 32804;
CREATE TABLE t1(c1 int, c2 VARCHAR(20));
INSERT INTO t1 VALUES (1, '1'), (1, '1'), (2, '2'), (3, '1'), (3, '1'), (4, '4');
INSERT INTO t1 SELECT 5 + 10000 * RAND(), '5' FROM t1;
INSERT INTO t1 SELECT 5 + 10000 * RAND(), '5' FROM t1;
INSERT INTO t1 SELECT 5 + 10000 * RAND(), '5' FROM t1;
INSERT INTO t1 SELECT 5 + 10000 * RAND(), '5' FROM t1;
INSERT INTO t1 SELECT 5 + 10000 * RAND(), '5' FROM t1;
INSERT INTO t1 SELECT 5 + 10000 * RAND(), '5' FROM t1;
INSERT INTO t1 SELECT 5 + 10000 * RAND(), '5' FROM t1;
INSERT INTO t1 SELECT 5 + 10000 * RAND(), '5' FROM t1;
SELECT c1, c2, COUNT(*) FROM t1 GROUP BY c1 LIMIT 4;
c1 c2 COUNT(*)
1 1 2
2 2 1
3 1 2
4 4 1
SELECT DISTINCT c2 FROM t1 GROUP BY c1 HAVING COUNT(*) > 1;
c2
1
5
DROP TABLE t1;
SET @@sort_buffer_size = @old_sort_buffer_size;
SET @@max_heap_table_size = @old_max_heap_table_size;
End of 5.1 tests
|